League leaders Gretna grabbed two goals in the final eight minutes of an end-to-end game that both sides finished with 10 men.
Ryan McGuffie was booked for a late challenge on Ayr defender Chris Robertson in the 29th minute and, two minutes later, Raymond Logan extracted revenge off the ball, leaving McGuffie stretched on the turf and earning a straight red.
Ten minutes after his departure Gretna made the extra man count when David Graham set up James Grady with a 50-yard run and a by-line pull back for the ex-Dundee United striker to score at the near post.
Ayr keeper Mark McGeown turned a David Nicholls drive away one handed before Ayr were denied a leveller by Gretna's Alan Main, who blocked a Gareth Wardlaw shot on the turn from 10 yards.
McGuffie was red-carded in the 54th minute when he tripped Craig Conway, but Gretna should have gone further in front. Normally reliable hit-man David Bingham fluffed a close-range shot with only keeper McGeown to beat after another good run and cross by Graham.
Gretna keeper Main turned away a fizzing drive by Ayr substitute Ian Cashmore, and Gretna defender Derek Townsley headed on to his own bar as the visitors pressed for an equaliser.
But, Graham with another run and cross set up Gretna's second in the 82nd minute, Dene Shields arriving at the far post to make it 2-0.
And Graham fittingly fired in Gretna's third from the penalty spot after Mark Casey handled a 90th minute free-kick by Steve Tosh.