Swansea had started the evening in third place, but they finished it in seventh as their winless home run extended to four games.

Brentford started brightly after being buoyed by their dramatic 3-2 weekend win over Millwall when they scored three times in the final eight minutes.

Ollie Watkins saw his low effort tipped around a post by Freddie Woodman and Josh Dasilva's goalbound drive was blocked by Borja Baston in a crowded goalmouth.

Swansea had been slow out of the blocks but winger Kristoffer Peterson raced past Henrik Dalsgaard to set up Yan Dhanda for a shot which was deflected on to the roof of the net.

Peterson provided the most dangerous moments for Swansea on his first league start.

The Swede had only played 69 minutes from the bench since his £700,000 summer move from Dutch club Heracles, but he again embarrassed Dalsgard before the move petered out and Swansea tried to get the ball to him as much as possible.

But Brentford took the lead on the half-hour as Christian Norgaard and Kamohelo Mokotjo played passes through the Swansea midfield.

Watkins laid the ball back to Mokotjo and he sprayed it wide for Benrahma to collect and score with a brilliant curler from just inside the area.

There was worse to come for Swansea six minutes later as Peterson's wayward pass was picked off by Watkins, who shrugged off Dhanda to advance.

Watkins attempted to find Bryan Mbuemo with a through ball but Bidwell, who scored only three goals in over 200 Brentford appearances, intervened to toe poke it into his own goal.

Swansea boss Steve Cooper responded to the chorus of boos at half-time by replacing Jay Fulton and Dhanda with George Byers and Bersant Celina, but Woodman was busy again to foil Julian Jeanvier and Watkins.

Peterson whistled inches wide from 20 yards but an error from Wales defender Joe Rodon, on his 22nd birthday, allowed Mbeumo to score for the second successive game with a clinical finish.

Benrahma and Watkins went close to adding to Swansea's discomfort before the hosts were denied a consolation when David Raya saved brilliantly from Byers at his near post.