Tam Courts praised his Dundee United players' commitment to the cause after their penalty shootout win at Ayr United in the Premier Sports Cup last 16.
Striker Tomi Adeloye gave the home side the lead at Somerset Park in the 55th minute in a game where David Hopkin's Championship side were a match for their Premiership opponents.
But with 10 minutes remaining Nicky Clark levelled from the spot after Ayr defender Jack Baird, booked earlier by referee Nick Walsh, was given a second yellow for a foul on Ryan Edwards inside the box, a decision which Hopkin hotly disputed.
The match went to extra-time and then penalties, where Clark scored the decisive spot kick for a 4-3 win.
Head coach Courts told DUTV: "I feel really proud of the players.
"I asked them at the start to find solutions. I knew it was going to be a ding-dong cup tie, there was a real carnival atmosphere and it was a game with a lot of thrills and spills and highs and lows.
"But these players are so committed to each other and so committed to the club and have proved time and again to find solutions and that's us in a quarter-final.
"I have got to commend the boys, we showed great bravery and resilience and quality in the end."
Tannadice keeper Ben Siegrist was the key man, making several saves during the 120 minutes before thwarting Patrick Ready and Jonathan Afolabi in the shootout.
Swiss keeper Siegrist said: "I felt I played well, I did my job, I did what I needed to do but it is a team game and the boys helped me massively.
"I am a big, tall goalkeeper so I fill up the goal quite well so that maybe plays a role as we saw in the Euros as well.
"I tried to put the taker off, decide which way I am going to go and go 100 per cent.
"You can only enjoy it if you win it at the end but I actually enjoyed it and I think the boys enjoyed it even though it was a tough game."
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