Scott Crabbe celebrates the opener

With 12 minutes gone, Ayr did take the lead after Lovering had been brought down in the area by Tassos Venetis.

Crabbe gave Gallacher no chance from the spot.

The quality of football was suffering as a result of the driving wind and rain at Ayr's backs.

Shortly after the half-hour mark, Dundee United had a series of chances to score.

Firstly Derek Lilley, then Steven Thompson and finally Venetis had shots blocked.

From the resultant corner, Lilley had a header saved and, seconds later, the striker hit the post with the Ayr defence in disarray.

At the other end, Sheerin hit a wind-assisted drive just wide after 40 minutes.

Then James Grady beat the offside trap and rounded the out-rushing Gallacher on the right, but he was unable to get a shot in on goal and the danger was averted.

Danny Griffin shows his disbelief

At the beginning of the second half, Gallacher gave his defenders a scare when he misjudged a cross in the wind but the ball was cleared before Robertson could capitalise.

Minutes later, Dundee United had another escape when Neil Duffy's header came back off the inside of Gallacher's post.

Charlie Miller had a vicious effort tipped away by Nelson as the visitors threatened at last.

Miller then created a good opportunity for himself on the edge of the box, but his shot was weak and easily taken by Nelson.

Paul Sheerin sealed Ayr's place in the semi-final with a marvellous individual goal in 80 minutes.

He picked up the ball midway inside the Dundee United half and ran at the visiting defence before curling a sweet left foot shot beyond Gallacher.

Hasney Aljofree shot just wide in the dying minutes as the SPL side searched vainly for a way back into the match.

Ayr United: Nelson, Hughes, Craig, Duffy (McEwan 57), Robertson, McGinlay, Wilson, Sheerin, Lovering, Crabbe (Kean 77), Grady (Sharp 90).

Subs not used: Scally, Dodds.

Dundee Utd: Gallacher, McCunnie, Lauchlan, Griffin, McCracken, Venetis (Carson 53), Miller, Easton, Hannah (Aljofree 80), Lilley (Winters 66), Thompson.

Subs not used: McConalogue, Jarvie.

Booked: Venetis, Lilley, Miller.

Att: 4,445

Ref: K Clark