On-loan Ranger Jukka Santala was Thistle's hero with two goals, including a late equaliser, but this was a game they should have won easily.
The Jags dominated for long stages and Santala was denied his hat-trick late on only by the lineman's flag.
Ayr raced ahead after six minutes when Jerome Vareille forced the ball home from close range after Andy Reid and Raymond Logan both had shots blocked in a packed penalty box.
Thistle were level after 25 minutes when Sean Kilgannon slid the ball across the face of goal and Santala raced in to guide the ball home.
Ayr regained their advantage seven minutes before the break thanks to Paul Hyslop, who touched the ball home from close range following a Reid cross.
Ayr had teenager Paul Weaver sent off five minutes into the second half after picking up two yellow cards in a heated 60-second burst.
Thistle stormed forward trying to make their extra man count and had several close calls before breaking through after 73 minutes. Substitute Graham Dorrans beat the Ayr defence on the touchline and cut the ball back for Santala to fire home.
Thistle then went all out for the winner, and Santala had the ball in the net again only to be flagged offside.
Thistle also finished with 10 men when Scott McCulloch was shown a straight red card for striking out at Ayr skipper Logan with five minutes to go.
Thistle boss Dick Campbell claimed: 'I don't think anybody at the game would have denied us a victory as we were by far the best side.'
His Ayr counterpart Robert Connor admitted: 'Too many players had off days, but we came away with a result because off our heart and commitment.'
On loan Ranger Jukka Santala was Thistle's hero with two goals, including a late equaliser, but this is gamer they shoyuld have won out the park.
The Meady Hill Jags dominated for long stages and Santala was denied his hat trick late on only by the linemans raised flag.
Ayr raced ahead in 6 minutes when Jerome Vareille forced the ball home from close range after Andy Reid and Raymond Logan both ahd shots blocked in a packed penalty box.
Thistle were level in 25 minutes when Sean Kilgannon slid the ball across the face of goal and Santala raced in to guide the ball home.
Ayr regained their advantage 7 minutes before the break thanks to Paul Hyslop, who touched the ball home from clo9se range following an Andy Reid cross.
Ayr had teenager Paul Weaver sent off 5 minutes into the second half after picking up two yellow cards in a heated 60 second burts.
Thistle stormed forward trying to makwe their extra man count and had several close calls before breaking through in 73 minutes. Sub Graham Dorrans beat the Ayr defence on the touchline and cut the ball back for Santala to fire home.
Thistle then went all out for the winner and Santala had the abll in the net again only to be flagged offside by the terracing linesman.
Thistle also finished with ten men when Scott McCulloch was shown a straight red card for striking out at Ayr skipper Logan with 5 minutes to go.
Thistle boss Dick Campbell claimed, 'I don't think anybody at the game would have denied us a victory as we were by far the best side.'
His Ayr counterpart Robert Connor admitted, 'Too many players had off days but we came away with a result because off our heart and commitment.'