Substitute Patrick Walker scored an 88th-minute winner as Dumbarton twice came from behind to win 3-2 at 10-man Airdrie.
Ryan Donnelly put the hosts in front after 15 minutes when he swept home from Willie McLaren's delivery.
Defender Alan Lithgow equalised for the visitors in the 34th minute, meeting Scott Agnew's inswinging corner to head into the net.
But the home side regained the lead just two minutes later courtesy of striker John Boyle's neat finish.
Three minutes after the interval Airdrie defender Cameron MacDonald was shown a straight red card for violent conduct following his challenge on Bryan Prunty.
Midfielder Agnew fired in from deep inside the penalty area to level things after 67 minutes before Walker, introduced in the 59th minute, scored from close range to grab the winner with just two minutes of normal time remaining.
Airdrie Utd: Fairley, Blockley, MacDonald, Stallard, Lovering, Bain, Lynch, Stevenson (Owens 74), McLaren, Boyle (Goodall 51), Donnelly (Sally 86).
Subs Not Used: Duncan,Holmes.
Sent Off: MacDonald (48).
Booked: Bain, Stevenson, Lovering, Owens.
Dumbarton: Grindlay, Finnie (Nugent 90), Lithgow, McNiff, Creaney, Gilhaney, Nicoll, Agnew, Lamont (Borris 79), Prunty, Graham (Walker 59).
Subs Not Used: Gastal, Wallace.
Booked: Nicoll, Lithgow, Creaney, Walker.
Ref: Mat Northcroft