Steven Lawless fired a controversial winner as Partick edged a five goal thriller at Firhill.
Ref David Munro was at the centre of controversy as United were left to rue some big calls which saw them lose out in Maryhill.
The Honest Men remain top of the Championship despite the reverse but were left wondering what might have been after a pulsating clash in Glasgow.
Boss Lee Bullen named a youthful bench which included five Academy graduates and a first place in the squad for under 18s midfielder Scott Tomlinson.
But United's threadbare numbers were able to make the perfect start when Akinyemi produced a moment of magic to fire them in front.
The striker collected a ball on the left touchline and, with seemingly little danger on, shifted inside before beating two men and rifling into the top corner from 20 yards.
The goal stunned Thistle after the hosts had made a bright start but they were able to regroup and get back on level terms when Harry Milne headed home a Kyle Turner corner.
Brian Graham then fired just wide as the hosts threatened to quickly turn the game on its head.
But Thistle were well on top and they forced their way ahead with the last action of the first half when Graham bundled home a Milne knockdown with Ayr screaming for offside against the striker.
That forced an interval switch from Bullen, who introduced Logan Chalmers for Sam Ashford - and the change had an immediate effect.
The on loan Dundee United winger produced a moment of magic straight from kick off as he shifted the ball on to his left before curling a brilliant effort into the far corner.
The game's breathless pace continued as Thistle went straight back in front after a huge moment of controversy.
Ref David Munro failed to give a free kick for a bad challenge on Ben Dempsey 25 yards out - although subsequently returned to book Thistle defender Darren Brownlie after seeing the damage done to the Ayr midfielder.
From the resultant Thistle restart, the Jags raced straight to the other end as Lawless converted an Aidan Fitzpatrick cross to rub salt in the Ayr wounds.
Ayr were immediately forced to replace the crocked Dempsey with David Bangala, while Brad Young was pitched on for Finn Ecrepont to add even more of an attacking threat.
And the on loan Villa striker should have made it 3-3 when pouncing on a spill from Jamie Sneddon but his effort was straight at the keeper.
And although United pushed late on for a point, they were ultimately left frustrated as thoughts now turn to the top of the table visit of Dundee on Friday night.
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