DJ Campbell struck in the 80th minute to hand his side a point in their Championship clash with Sheffield Wednesday at The Den, while both sides ended the game with 10 men.
Ian Holloway's side were on top as the start of the game as Steve Morison was played in behind the visitors' defence, but he couldn't find the target as he fired his shot just wide of the post.
Millwall should have taken the lead in the 22nd minute when Andrew Keogh raided down the flank and crossed into the box for Lee Martin, but his effort was saved by Chris Kirkland from close range.
The home side nearly rued the missed opportunities when Jeremy Helan robbed Nicky Bailey in the midfield and lifted the ball into the area for Atdhe Nuhiu only for him to head the ball over the bar.
After the break, Millwall came so close to taking the lead as Morison looped a header towards goal and his effort looked to be creeping into the net, but Kirkland somehow got a hand to the ball to turn it away.
The home side were on top but it was Wednesday who took the lead against the run of play as they hit the Lions on the counterattack, and Giles Coke was left with a simple finishing collecting a through-ball on to the area, which he fired past Bywater.
Stuart Gray's side almost made it two minutes later as Miguel Llera headed at goal but Bywater saved to keep his side in the match.
That save would be crucial as Millwall got their equaliser as Campbell found the net with a diving header, latching on to Liam Trotter's cross into the penalty area.
The game ended on a sour note for both sides as Coke and Shane Lowry were sent off for an altercation at the corner flag, but the game still ended all square.
Simon Sinclair
