Said Benrahma doubled Brentford's advantage after 26 minutes, guiding the ball into an empty net after Bentley had kept out shots from Mathias Jensen and Watkins.

Any doubt about the outcome was ended after 82 minutes when man-of-the-match Watkins tapped home a low cross from substitute Jan Zamburek.

Watkins still had time to add the fourth, drilling home a low shot as stoppage time approached after Bentley had done well to parry his header.

The result saw Brentford rise to third in the table while City slipped to 11th following a fourth defeat in five games.

The first half-hour was a New Year nightmare for Robins head coach Lee Johnson, who was loudly booed by home fans when electing to withdraw in-form winger Niclas Eliasson to shore up his under-manned defence in the 28th minute.

Taylor Moore went on as a substitute to partner Tomas Kalas in central defence, with Korey Smith – who had dropped into the position after Williams' dismissal – reverting to midfield in a 4-4-1 formation.

Brentford dominated possession but City's 10 men threatened on occasions, David Raya saving from Jay Dasilva and Marley Watkins.

Christian Norgaard fired wide with an acrobatic bicycle kick for Brentford, who were largely content to retain the ball and protect their two-goal lead.

Thomas Frank's team almost made it 3-0 at the start of the second half, the dangerous Watkins heading wide and then wasting a chance gifted to him by an Andreas Weimann back-pass.

With only Bentley to beat, Watkins delayed his shot to try and round the keeper, allowing Kalas to get back and dispossess him.

There was no faulting City for effort, with Famara Diedhiou showing huge work-rate as a lone striker.

But Brentford continued to carry the greater threat. Watkins had another header deflected over the bar and Bentley made a fine save when Ethan Pinnock nodded down at the far post from a left-wing corner.

Watkins' goal capped an impressive individual effort and Frank's men defended solidly throughout to gain a well-deserved result.