Cole McKinnon’s early screamer went unrewarded as the much-improved Diamonds fell to a frustrating late defeat at Firhill.

A late substitute-inspired rally by Partick Thistle saw Airdrie’s hunt for a Championship win go on, but there were encouraging signs as the squad adjust to life under Danny Lennon.

One-time Thistle loanee McKinnon was handed his first start for the club after making his debut from the bench at Arbroath a fortnight ago, with Jamie Barjonas also returning to the starting XI. Dean McMaster and Rhys Armstrong were the players to make way.

Ex-Diamonds Josh Clarke, Ben Stanway and Tony Watt lined up for a Jags side managed by former Airdrie boss Mark Wilson.

A strong start for the visitors saw a Chris Mochrie strike deflected wide with just 23 seconds on the clock. Although Charlie Telfer’s corner kick would be adequately dealt with on this occasion, the midfielder got another chance two minutes later.

As the delivery from the Airdrie left was nodded to the edge of the box, McKinnon took possession, sidestepped referee Grant Irvine, and blasted home a 20-yard effort which left Clarke rooted to the spot as it whistled into the net.

As Thistle began to find their feet, Lewis Strapp was proving effective in defence and attack for the Diamonds, winning possession on nine minutes before going on a promising run which was ultimately snuffed out.

McKinnon had another go at goal three minutes later, again acting as the spare man as Lewis McGrattan was crowded out, but on this occasion his strike was too high.

Watt had Thistle’s first meaningful chance, coming out on top after a duel with Sean McGinty, but the former Airdrie youngster sent his shot off-target.

Watt was again the focal point for the hosts’ attack on 14 minutes, but McGinty closed down well, with Matty Connelly holding a header from the Thistle strike two minutes later.

Aidan Wilson halted Robbie Crawford’s direct running with a well-timed tackle midway through the first half, and Craig Ross did well to recover moments later as the Maryhill side enjoyed some attacking pressure.

McGinty was on hand to head out a goalbound corner before Connelly mopped up a bad touch from Watt with 26 minutes played.

Mochrie and Daniel O’Reilly exchanged half chances before Telfer saw a shot blocked on the half-hour mark.

As the pendulum swung in Airdrie’s favour again, McKinnon’s through-ball for Mochrie was well cut out before McGrattan saw an effort from range deflected wide.

Wilson’s timing in the tackle proved vital again on the stroke of half-time, and a superb reflex save from Connelly denied Ts’oanelo Lets’osa in first-half stoppage time to keep the Diamonds ahead at the break.

The second half began in end-to-end fashion, Barjonas putting just too much on a clever chipped pass on 48 minutes before determined defending saw off a Thistle chance three minutes later.

Telfer had the ball nicked from his toe as he lined up a 54th-minute shot, and a minute later some superb harrying from Mochrie saw a home defender forced to pass back to Clarke, who picked the ball up – an action which somehow went unpunished.

McGrattan was unlucky to lose out following a collision after Mochrie had won possession with a brilliant sliding challenge, and Euan Henderson sent a shot over the top after Wilson had returned a 65th-minute Telfer corner.

Four substitutions gave the home side a much-needed spark, with former Diamonds loanee Kyle Turner sending in a dangerous free-kick on 70 minutes before Steven Lawless almost found fellow sub Alex Samuel three minutes later.

A 75th-minute corner was well met by Lee Ashcroft, but the centre-back sent his header well wide of the post.

There was no such profligacy two minutes later as another good corner delivery found Daniel O’Reilly, and the former Hamilton defender powered his header into the net for the equaliser.

Five minutes later the Diamonds were still regrouping having lost the lead they had held for so long, and striker Samuel was on hand to punish the visitors – turning home from 15 yards after a defensive block had fallen kindly for the former Ross County man.

Airdrie sub Cammy Cooper saw a deflected effort loop toward goal with two minutes remaining, but a covering defender was able to head off the line.

Clarke claimed well as Tate Xavier-Jones challenged for a last-minute header, and some good defending kept out a curling Strapp effort in stoppage time.

The final whistle signalled a cruel defeat for the Diamonds, who had looked on course for a long overdue win at Firhill until the home side’s late salvo.

A return to the Albert Bartlett Stadium is next up for Airdrie, with Raith Rovers the visitors in a week’s time.