Dumbarton take a slender advantage into the second leg of their First Division play-off final after a thrilling win at home to Airdrie United.
But they will be missing Paul Nugent through suspension after their captain was sent off in the dying seconds.
Former Airdrie striker Bryan Prunty fired Sons' 29th opener and Tony Wallace headed in three minutes later.
But Jamie Bain slotted Airdrie's reply after his 42nd-minute penalty was saved but not held by Stephen Grindlay.
Airdrie, who have built a reputation of losing play-offs in recent seasons, finished fourth below the Sons in the Second Division table this season but started the brighter of the two sides.
However, the side looking to reach the second tier of Scottish football for the first time in 16 years scored twice within three minutes.
First, Prunty gathered a Mark Gilhaney cross before firing into the top corner from 12 yards.
Then Scott Agnew's curling free-kick into the penalty box was flicked into the net off the head of Wallace.
Airdrie, who in their semi-final had consigned Ayr United to relegation after beating the side that finished ninth in Division One, were firmly back in the match three minutes before the break.
Wallace pulled down Jamie Stevenson mid jink and, although Bain's spot kick was parried by goalkeeper Grindlay, he converted the rebound.
That inspired Airdrie after the break and Stevenson forced Grindley to turn his 18-yard drive over the crossbar with his fingertips.
The midfielder once of Real Mallorca also sent another powerful effort flashing across the face of goal.
In between those efforts, Scott Agnew had a drive from distance turned over by on-loan Rangers goalkeeper Grant Adam.
Dumbarton, who had beaten second-placed Arbroath in their semi, settled and only Adam's outstretched leg prevented Pat Walker stretching the lead as the striker bore down on goal.
When Adam misjudged a Mark Lamont cross, Prunty should have done better than head into the side-netting at the back post.
It was now an end-to-end affair and, after a Derek Holmes knock-down, much-proclaimed Airdrie forward Ryan Donnelly shot high and wide on the turn.
Prunty squandered another chance to increase Dumbarton's advantage when he was through on goal but had his effort blocked by the body of Adam.
Airdrie raced up the other end and Nugent was sent packing after picking up his second yellow card for a cynical challenge on Airdrie substitute Willie McLaren in what was virtually the last kick of the game.
Dumbarton: Grindlay, Nugent, Creaney, Lithgow, Wallace (Gray 85), Agnew, Nicoll, McNiff, Gilhaney (Lamont 39), Prunty, Walker (Graham 72). Subs Not Used: Ewings, Kennedy.
Sent Off: Nugent (90). Booked: Wallace, Creaney, Nugent.
Goals: Prunty 29, Wallace 32.
Airdrie Utd: Adam, Stallard, Lovering, MacDonald (McNeil 46), Lilley, Lynch, Bain (McLaren 72), Blockley, Stevenson, Holmes, Donnelly (Boyle 86). Subs Not Used: Duncan, Lamie.
Booked: Lovering, Blockley.
Goals: Bain 42.
Ref: Iain Brines