Andre Ayew netted his 16th goal of the Championship season against 10-man Brentford in the semi-finals of the playoffs.
Swansea were playing at home in the first leg and needed a late strike from the Ghana captain to give the Swans the advantage ahead of the second leg.
Ayew, who had the chance to give Swansea a lead earlier in the second half from the penalty spot, had been faultless from the spot during the 2019-20 campaign, but he was denied by Raya’s trailing right hand to keep the scores level.
The match took a dramatic turn a couple of minutes after the penalty miss as Brentford’s Henry was shown a red card for a rash challenge on Roberts near the right-hand touchline.
With less than 10 minutes to go, Ayew made amends by firing Swansea ahead with a well struck volley.
Swansea City head to Griffin Park with the advantage in the play-off semi-final against Brentford on Wednesday night.