Anthony Marenghi struck with a superb free-kick as 10-man Ayr secured a third straight win, 1-0 at Airdrie.
In a tight first half, Airdrie keeper Scott Gallacher dealt with a 30-yard Scott McLaughlin free-kick but had to rely on the crossbar to keep out a Marenghi set-piece strike from even further out.
At the other end, Martin Hardie fired in a solid effort from 25 yards which forced Ayr shot-stopper David Hutton to make a fine save, but it remained goalless at the interval.
Ayr were soon in front after the break, though, as Marenghi fired in a free-kick from the edge of the area, although they were down to 10 men after having Kyle McAusland sent off for a second bookable offence.
As the rain poured down at Excelsior Stadium, Airdrie tried hard to make their man advantage count but couldn't find a cutting edge up front and fell to a fifth defeat in six games.