Match ends, Dundee United 3, Dunfermline Athletic 1.
Extra-time goals from Scott Fraser and Blair Spittal helped Dundee United gain their place in the last eight of the league cup against a spirited Dunfermline.
Michael Paton scored his first goal for Dunfermline in the first half to give them the lead.
Callum Morris headed an equaliser for the home side before the break.
The game went to extra-time but as the Pars ran out of steam Fraser and Spittal netted to settle the tie.
It was a long awaited win for Jackie McNamara's side as they make it into Monday's quarter-final draw.
Dunfermline though will rue two missed chances from Ryan Wallace that could have seen them take a Premiership scalp.
The League One side have been free-scoring so far this season with 41 goals in their opening 11 matches and within the opening two minutes top scorer Faissel El-Bahktoui fizzed in a shot from 20 yards that was straight at United goalkeeper Luis Swick.
They deservedly took the lead although they had a huge slice of fortune for the goal.
Paton collected a pass from Joe Cardle 25 yards from goal. His shot was straight at the United 'keeper, but inexplicably he allowed the ball to slip through his hands and into the net.
It was a dreadful mistake and a blow to a United side who were already lacking in confidence with only one win in their opening eight matches.
Slowly the home side crept into the game and Fraser and Charlie Telfer came close to an equaliser, before it eventually came from former Dunfermline defender Morris.
The Pars makeshift defence failed to clear a corner and Morris found space inside the six yard box to head home.
Wallace missed a glorious chance on the stroke of half time that would have put Dunfermline in front when he slipped the ball beyond the far post with the goal gaping.
The winger made a terrific run that beat the United offside trap. He took the ball around the keeper but with an open goal facing him he slipped the ball the wrong side of the far post.
United manager McNamara may well have had some strong words for his players and they certainly started the second period with a flourish.
Billy McKay and substitute Spittal both came close for the home side before Dunfermline goalkeeper Sean Murdoch pulled off a succession of saves to keep his side in the game.
Dunfermline also had their chances as El-Bahktoui curled the ball just wide of goal after Michael Moffat had his chance blocked.
With the last attack of the 90 minutes United were denied again when Murdoch saved from Simon Murray as the former Arbroath striker looked set to score with a header.
The home side eventually took the lead in extra-time thanks to a wonderful solo effort.
Fraser evaded the challenge of four Dunfermline defenders before guiding the ball beyond the helpless Murdoch and at last the home fans could breathe easy.
And the tie was put to bed when Spittal cut in from the left hand side before curling a left foot shot into the corner to send United into the next round.
Dundee United manager Jackie McNamara: "The important thing is we're in the next round.
"As you would expect we were nervous at the start but we grew into it.
"I thought Dunfermline started the game better than us. Once we settled down and moved the ball we caused them problems.
"Dunfermline tonight had a fantastic crowd up and they can be proud of their team."
Dunfermline manager Allan Johnston: "I thought it was a brilliant team performance from start to finish. We caused Dundee united a lot of problems and on another day I think we'd have got the win.
"We defended well for long periods, we broke well, created chances. The boys couldn't do anymore.
"With that type of performance against a Premiership team, I think the boys showed the quality they've got."
- 5MorrisBooked at 31mins
- 17DurnanBooked at 29mins
- 16TelferBooked at 60minsSubstituted forSpittalat 61'minutes
- 25KuhlSubstituted forTaggartat 73'minutes
- 30BodulSubstituted forMurrayat 73'minutes
- 2GegganBooked at 90mins
- 3TalbotSubstituted forMcCabeat 81'minutes
- 8ByrneSubstituted forHopkirkat 45+46'minutes
- 11CardleBooked at 77mins
- 9WallaceSubstituted forMoffatat 68'minutes
- 10El BakhtaouiBooked at 29mins
- John Beaton
- Shots on Target
Second Half Extra Time ends, Dundee United 3, Dunfermline Athletic 1.
Foul by Simon Murray (Dundee United).
David Hopkirk (Dunfermline Athletic) wins a free kick in the defensive half.
Attempt missed. Faissal El Bakhtaoui (Dunfermline Athletic) right footed shot from the centre of the box is just a bit too high.
Attempt saved. Blair Spittal (Dundee United) left footed shot from the right side of the box is saved in the centre of the goal.
Foul by Scott Fraser (Dundee United).
Joe Cardle (Dunfermline Athletic) wins a free kick on the right wing.
Luis Maria Zwick (Dundee United) wins a free kick in the attacking half.
Foul by Joe Cardle (Dunfermline Athletic).
Foul by Adam Taggart (Dundee United).
Lewis Martin (Dunfermline Athletic) wins a free kick in the attacking half.
Foul by Scott Fraser (Dundee United).
Josh Falkingham (Dunfermline Athletic) wins a free kick in the defensive half.
Attempt saved. Blair Spittal (Dundee United) left footed shot from the right side of the box is saved in the bottom left corner.
Second Half Extra Time begins Dundee United 3, Dunfermline Athletic 1.
First Half Extra Time ends, Dundee United 3, Dunfermline Athletic 1.
Adam Taggart (Dundee United) wins a free kick in the defensive half.
Foul by Rhys McCabe (Dunfermline Athletic).
Attempt missed. Faissal El Bakhtaoui (Dunfermline Athletic) left footed shot from the centre of the box is close, but misses to the left.