Live Commentary: Serena Williams vs. Victoria Azarenka - as it happened

Good afternoon! Two women who will both believe that they can win the title go head to head in the Wimbledon quarter-finals shortly as world number one Serena Williams takes on two-time Grand Slam winner Victoria Azarenka on Centre Court.

It's been a couple of years since either player reached the business end of Wimbledon. Williams had reached the quarters in just one of her previous four appearances at SW19. However, she has won the title three times in the last six years, so will be confident now that she is in the last eight.

Azarenka reached back-to-back semi-finals in 2011 and 2012, but a knee injury forced her to pull out after the second round in 2013, before a foot injury curtailed her run in 2014. Her ranking has dropped a bit over the last 18 months while she's struggled through injuries, but she's on the rise, and will be hoping to reach a semi-final for the first time since the 2013 French Open.

The players make their way out onto court. It's a little quiet around Centre Court at the moment as fans take a quick break following a lengthy match between Maria Sharapova and Coco Vandeweghe, but you can guarantee they'll be heading back in once the players have gone through their warmups.

Azarenka beat the world number one twice during 2013 before hitting a run of injuries. Just last month at the French Open through, she pushed Williams close in three sets. The Belarusian has won just three of their 19 previous meetings though, including all three on grass.

There's another last-eight match underway on Court One at the moment as well, with 2012 runner-up Agnieszka Radwanska taking on young American Madison Keys. You can follow live updates from that match here.

Azarenka hasn't really been talked about as a potential title contender, but she hasn't dropped a set yet at this tournament. Williams has had a couple of tricky matches, scraping through against Heather Watson before having an emotional meeting with sister Venus Williams in the fourth round.

Right then, the players are ready to begin, with Azarenka serving first.

Azarenka makes a strong start, picking up the opening couple of points, but Williams hits back with some powerful returns, but a double fault from the Belarusian hands the top seed a chance to break. Williams hits her return wide on the next point though to take the game to deuce. A volley close into the net hands Azarenka advantage, before a big serve results in another long return from the top seed, allowing Azarenka to escape with her serve intact.

Williams hits her first ace of the match with just her second serve, before Azarenka catches the ball with the frame of her racquet. At 40-0, Azarenka can only slice the ball into the net on the return, handing Williams a comfortable hold.

Williams is really going for the power on her forehand early on in this match, but she twice overhits the ball, before landing one perfectly on the sideline, which the Belarusian can only slot into the net as she stretches to reach it. Williams gets another point back, but Azarenka comes into the net for a volley, which the world number one can only scuff into the net.

BREAK! Azarenka attacks as she pushes in from the baseline, taking her forehands early before landing one on the sideline to bring up two break points. A big serve from the world number one saves the first, but a low backhand from Williams on the next point hands Azarenka the game.

Azarenka struggled with her serve in the first game, but she serves beautifully this time around, racing to 40-15 as she forces a long return from Williams, before sealing the game with her first ace of the match.

It's a change of ends on Centre Court, and a change of shift for Sports Mole, but don't go anywhere, as Charlie Bennett will be here to talk you through the rest of the match.

Thank you Sian, and what a match this is turning into folks! Williams finds her first serve again as he moves 15-0 up, before she cracks an unbelievable backhand down the line. Azarenka hits a superb return to get to 30-15, but the top seed sees the game out with some big serving.

It's a good start from Williams in this game as she forces Azarenka to hit a tame backhand into the net. However, the two-time Grand Slam champion digs deep to make Williams hit a forehand out of play, before firing down an ace. Two more first serves force Williams to hit two returns out of play, and she's now just one game away from taking the first set.

Serena now has the task of serving to stay in the set and she gets off to a good start with an ace. Azarenka gets lucky off the net-cord to reach 15-15, before Williams serves a double fault! Some more excellent tennis from Azarenka sees her earn two set points with a winner down the line, but Williams saves the first and lets an almighty roar. Azarenka then sends a backhand out of play to take it to deuce, and Serena whacks a backhand into the corner to move ahead. Azarenka nets a forehand next time around, and Williams holds on. Just.

SET! Don't give Serena any second serves to hit! Williams cracks a weak Azarenka serve into the corner to move 0-15 ahead, but the Belarus star quickly regains composure to move within two points from the first set. A double fault brings it back to 30-30, before an incredible point of power-hitting is won by Azarenka. She then claims the first set with another vicious backhand, which Serena can only watch and admire. It's game on here!

Serena won't be ruffled, but she'll be concerned at how brilliantly Azarenka is playing. The 20-time Grand Slam champion powers down two aces to start the second set, before Azarenka hits one out of play. A third ace flies past Azarenka's racket, and it's a good start for Serena.

Good start to the set from Azarenka, who picks up where she left off with powerful groundstrokes. Williams can't cope right now, and Azarenka comfortably holds.

Just look in her match with Heather Watson last week, Serena is desperate to shake herself into action. She lets out an almighty shriek when she goes 30-15 up, but Azarenka responds with a brilliant forehand. The level of Williams' scream goes up and up during the next point, and she lets out another roar when she belts a forehand cross court win the point. She wraps the game up next time round, and she looked something like back to her best there!

What a game of tennis! Azarenka double faults AGAIN at the beginning of the game, but she recovers to crash a backhand up the line for a clean winner. Williams hits back with some powerful groundstrokes, and she finishes the point with a driving volley at the net. The decibel level of their screams goes up and up during the next point, much to the amusement of the crowd, but Azarenka wins it with a accurate volley down the line. Williams takes it to deuce, but she can only put a slice in the net as Azarenka's intense hitting gets the better of her. The tennis is just getting better and better now, as Williams darts forward to squeeze a shot cross court for a winner, before she earns a break point when Azarenka nets. Can she take it? NO! She squanders the chance as she over-hits a forehand, but she earns a second with a brilliant backhand winner. Azarenka survives for a second time, and then again for a third time when Williams chips long. Finally, Azarenka earns game point but we go back to deuce again as Williams sends a forehand down the line. Azarenka wins the next two points to hold on though, and that could be crucial.

This is just getting more dramatic with every game! Williams races into a 30-15 lead, but two silly unforced errors gives Azarenka break point. A powerful second serve is finished off with a volley by Serena to go to deuce, before she hits an eighth ace of the match. A backhand winner sees her cling on, and both sit down for a much-needed break.

BREAK! So, who's going to crack first in this deciding set? The first two points are shared in this game, before Azarenka moves ahead with a winner and a bad Williams error. Williams gets back into things when Azarenka hits two forehands out of play. Another error gives Williams break point, but the American clips a backhand wide. She gets another chance two points later, and she finally does it!! Azarenka sends a volley into the net, and she goes 4-2 up!

Williams needs to hold serve here, otherwise all her hard work will result in nothing. A poor backhand and a double fault moves Azarenka 15-30 up, before a tepid forehand from Serena limply hits the net. Azarenka misses a golden opportunity to win the game as she blazes a forehand out of play, while Williams follow that with a smash to take the game to deuce. Williams holds on to win the game, and Azarenka will rue that missed chance.

SET! This is a big game for Azarenka, as she'll be desperate to force Williams to serve out the set herself. She gets off to a nervous start but reaches 15-15, before she sends a volley badly wide to give Williams another chance to break. Two big serves wrestles back the momentum, but Williams hits an unbelievable forehand to take the game to deuce. Williams is starting to win these big rallies now, and she forces a set point. Azarenka can't contain her power, as she nets a forehand and we're all level again!

So, we have a final set shoot-out! Williams serves first, and she starts positively with a big serve and a booming backhand to go 40-0 up. A wild forehand gives Azarenka a point, but Williams holds on to win the game.

BREAK! Azarenka needs to stop Williams's momentum here, but the game starts badly as the American hits a backhand past her and she hits an unforced error. Serena loses the next point to give Azarenka hope at 15-30, before a wild backhand levels the score. A big forehand catches the baseline to give Williams a break point, and she takes it as Azarenka hits a backhand wide. The former world number one can't handle Williams in this form.

Williams is motoring now, as an Azarenka unforced error and a big serve puts her 30-0 up. The Belarus star thinks she's won the next point with a deadly passing shot, but Williams sticks out a long arm to tip a volley over the net. Another ace gives her a commanding lead, and she's just three games away from the last four.

This is a must-win game for Azarenka, who has lost the last seven in a row. But when Williams is timing backhands as well as this, winning a point is difficult. The American sweetly dispatches one down the line to take the score to 15-15, but Azarenka responds with a well-struck winner of her own. Williams is just too good right now though, as she hits another winner and then forces a break point. Azarenka saves it with a big second serve which Williams can only net, and she holds on to win a gutsy game. She yells "Come on", and the crowd responds with loud applause.

On this form, can anyone stop Serena Williams? The American hits four first serves which Azarenka can do little with to move 4-1 ahead. After that gutsy hold last time out, Azarenka must be deflated.

Azarenka is just not playing at the level she was at earlier on, but she's still fighting and manages to hold serve again. Williams is letting rip at every opportunity, but in this game they fail to find their mark.

This is just phenomenal serving from Williams, who hits three aces and a vicious winner. The American looks destined to face Maria Sharapova on Thursday, unless Azarenka can find a miracle.

Williams is just one game away, and she clearly doesn't fancy hanging around to serve it out herself. She wins the first point with an accurate backhand, but marginally misses with a return of serve next time round. Azarenka does a couple of fist pumps when Williams hits the net with a forehand, but the American manages to the game to deuce. A sweet shot and an ace give Azarenka the game though, and Williams will now serve for the match.

GAME, SET AND MATCH Williams is just four points away from the semi-finals, but she starts with a double fault. Azarenka then takes advantage of a bit of luck as Serena hits the net-cord, and she punishes her with a forehand into the corner to go 0-30 up. Two Williams aces brings it back to 30-30, but she then slams a smash into the net to give Azarenka break point!! But again Williams hits a monster serve to take it deuce, before she earns match point. She's won it!!! Azarenka hits a forehand wide, and the match is over!

What a brilliant game of tennis! Williams was made to work very hard by a brilliant Victoria Azarenka, but she showed plenty of guts to battle through. Next up for her is Maria Sharapova, who she lost to in the final back in 2004.

What a day of tennis it has been, and you can follow even more with us tomorrow when the men take centre stage. Andy Murray, Roger Federer, Novak Djokovic and Stanislas Wawrinka are all in action and we'll be bringing you more live coverage. That's it from me today though, so we'll see you tomorrow. Have a good night.