This was a result as dramatic as it was controversial as Jaroslaw Fojut's winner in added time last night put Dundee United into the fourth round of the League Cup after a compelling tie at Tannadice.

A corner from Gary Mackay-Steven from the right, a final attack from the home side as Dundee - down to 10 men from midway through the first half - held on under increasing pressure found the head of the towering Polish player who thundered his effort in to the net.

However, it was the ordering off of Martin Boyle after 27 minutes which took the fizz out of this game. Paul Hartley, the Dundee manager, complained bitterly that referee Craig Thomson called it wrong when he said the forward was guilty of a last-man trip on Stuart Armstrong.

Indeed, Hartley's expression before a ball was kicked was indicative of his feelings three days after he watched his side surrender to their neighbours when they met in the league just up the road at Dens Park - United hammering home their superiority with a 4-1 victory.

The Tannadice side introduced Blair Spittal, Armstrong and Nadir Ciftci - returning from a two-match suspension - to the starting XI last night, while the Dark Blues made two changes; Gary Harkins and Philip Roberts were among the substitutes as Luka Tankulic and Boyle were brought in to re-energise their side.

It was a sizzling 18-yard strike from the latter which, had it not been for Radislaw Cierzniak's acrobatic save in the fifth minute, would have given Dundee the opener. The United goalkeeper knew little of Thomas Konrad's volley from the resultant corner, although his legs were in the right place to deflect the effort.

This was an up and at 'em approach by the visitors whose tempo was high and their determination clear as they went for United's throats. However, when John Rankin fouled Paul McGowan in the area after 18 minutes and a penalty was awarded, they squandered the opportunity as Cierzniak delivered again to thwart Greg Stewart from the spot.

If Hartley was irked, then Jackie McNamara, the United manager, must have been positively fuming with the defensive frailties in his side and their inability to subdue their rampant opponents.

Then came Boyle's departure, a combination of over-exuberance and lack of thought, his last-man trip on Armstrong - according to Thomson, at least - bringing an immediate red card and a tactical re-think by his manager.

United's use of the ball during the second half was attractive and they hoped to capitalise on the weary legs of the Dens Park side. But, if McNamara preached patience, Hartley hoped for a break and a potential error from the solid home defence during one of the infrequent attacks his side mustered after the break.

McGowan's clever chip looked promising for a moment before it hit the top of Cierzniak's goal, while Roberts, on for Tankulic on the hour, worked hard to inject some oomph into his team's play. When he sent a low ball across goal James McPake just failed to make contact.

However, the killer blow was delivered by Fojut, too late for Dundee to recover as United triumphed in a second derby in three days.