Falkirk lost star striker Lyle Taylor but still ran out winners against Airdrie.
The Londoner hit his 27th goal of the season to hand the Bairns three points in the 58th minute.
But interim boss Alex Smith lost his talismanic forward shortly after as he was sent off for an off-the-ball skirmish with Diamonds defender Gregor Buchanan on 67 minutes.
Few in the ground saw the incident, but ref Mat Northcroft was alerted by his linesman and showed the prolific Englishman his second yellow card.
The first had come before the break for simulation, as Taylor tumbled theatrically alongside Rickie Lamie. While there appeared to be contact, Northcroft believed Taylor’s yelp and flailing arms warranted a caution.
It was one of few flashpoints in the first half dominated by Falkirk’s passing, but rarely penetrated by it.
The Bairns had Airdrie chasing shadows for the opening 45 but couldn’t beat ex-Stenny goalkeeper, and Falkirk local, Robbie Thomson.
Falkirk went close midway through the first half but first Jay Fulton slid a shot over, but he was then pivotal in the move that gave Alston a strike at goal. The middle of the three Falkirk brothers flicked on Conor McGrandles pass to Kieran Duffie to release the right-back and a great cross was fired at goal by Alston but blocked by Buchanan.
The midfielder didn’t return for the second half and was replaced by David Weatherston, but Buchanan, who blocked was involved in the Falkirk goal. He was pressured by Stewart Murdoch and took one touch too many before turning to play a pass-back out of trouble. It only played him into trouble as Lyle Taylor read the move and raced onto the short pass and homed in on Thomson. The striker stopped, paused and hesitated before lashing into the top corner of the net.
But a re-run of the hat-trick he claimed here in December was not to be as the striker was booked for a second time for an incident in the corner of the park on 67 minutes.
Falkirk rang the changes after surviving ten minutes with a man deficit and swapped Sean Higgins for Thomas Grant. Darren Dods went close with a header, then the sub did the same, and though Airdrie right-back Chris O’Neill blazed the best chance of the game over in stoppage time there was to be no breaching Michael McGovern. The goalkeeper was clattered three times and needed treatment twice and flew off his line to punch and block everything Airdrie threw at him.
Falkirk’s next match is on Tuesday evening when the Bairns will travel to Almondvale to take on Livingston.
Meanwhile, Stenhousemuir’s hopes of reaching the Second Division play-offs suffered a blow on Saturday as The Warriors lost 1-0 at home to basement side Albion Rovers. Martyn Corrigan’s side are now six points away from fourth place with as many games left to play.
There was more misery for East Stirlingshire, who lost 2-0 away to Clyde. The result leaves John Coughlin’s side three points adrift at the foot of the Third Division table.