A brace from Stevie Crawford and a Barry Nicholson winner completed an amazing second-half recovery as Aberdeen progressed to the Tennent's Scottish Cup fourth round at Dundee United's expense.

David Fernandez had fired United into a two-goal lead when he first bundled Collin Samuel's cross over the line in the 26th minute, before grabbing another two minutes later, again from Samuel's pass.

However, Derek Stillie's fumble gifted Crawford his first in the 64th minute and after the former Dundee United striker sidefooted his second five minutes later, Nicholson struck with 11 minutes left to send the Pittodrie side through.

Despite their collapse midway through the first half, Aberdeen started in positive fashion and an enthusiastic run from Chris Clark set up a half-chance for Nicholson, via a neat pass from Steve Lovell.

When the former Dundee striker's touch found the midfielder positioned 10 yards out, Nicholson immediately launched an instinctive snap-shot towards goal which just cleared the home side's crossbar.

The next 15 minutes saw two evenly-matched teams cancel each other out, before the Dons peppered the home goal with a succession of shots after Gary Dempsey's cross from the byline caught the United defence cold.

Crawford saw his initial effort parried by Stillie and when Lovell's blocked follow-up fell to Kevin McNaughton, the midfielder shot over from the edge of the box.

However, in a frantic two-minute spell, United sprinted into a two-goal lead courtesy of a double from Fernandez.

The first goal came when Samuel managed to drive a low cross from a tight angle between Jamie Langfield and his near post, which was met by the former Celtic forward who bundled the ball over the line with his upper torso.

That strike clearly rocked the fragile confidence of the away side and Jimmy Calderwood's outfit proceeded to self-destruct when they presented a second goal on a platter to the rampant Fernandez.

Russell Anderson's throw-in played Clark into all sorts of trouble and his misplaced pass landed straight at the feet of the sprightly Samuel.

The Trinidadian forward wasted no time in splitting the Aberdeen defence wide open with a neat through-ball and the Spaniard comfortably beat Langfield from the edge of the box with a left-footed effort.

Fernandez then attempted to round off a first-half hat-trick with a curling free-kick which was heading for the top corner of the net, but he was denied by a fantastic stop from Langfield.

United started the second half on the front foot and should have secured victory when Samuel was presented with a free header only six yards from goal from Stuart Duff's cross.

But somehow the striker sent his header wide despite being completely unmarked.

That miss was to prove extremely costly two minutes later as United goalkeeper Stillie gifted the Dons an equaliser when he fumbled Richie Byrne's cross, leaving Crawford with an easy tap-in - before the Aberdeen striker drew his side level in the 69th minute.

Byrne was again the architect, delivering a cross from the left-hand side and when the ball fell to Crawford, he calmly sidefooted home from 10 yards out.

However, Aberdeen's recovery was not yet complete and 10 minutes later good work from Crawford allowed substitute Richie Foster to pick out Nicholson who was lurking six yards from goal.

The former Dunfermline midfielder applied an assured finish to the move, easily beating Stillie and sent Aberdeen through to the fourth-round draw.

Teams

Dundee Utd Stillie, Wilson, Duff (Miller 82), McCracken, Archibald, Kerr, Mulgrew, Robson, Fernandez, McIntyre, Samuel.

Subs Not Used: Samson, McInnes, Brebner, Kenneth.

Booked: Kerr.

Goals: Fernandez 26, 29.

Aberdeen Langfield, McNaughton, Griffin, Anderson, Byrne, Smith, Nicholson, Dempsey (Foster 45), Clark, Crawford (Considine 85), Lovell (Mackie 59).

Subs Not Used: Esson, Stewart.

Booked: Nicholson, Langfield.

Goals: Crawford 64, 69, Nicholson 79.

Att: 8,218

Ref: S Dougal (Scotland).