Albion slipped to consecutive Premier League defeats as an Ivan Toney brace secured all three points for Brentford on Friday.
Roberto De Zerbi's side had their chances with Solly March, Leo Trossard and Lewis Dunk all denied by brilliant saves from David Raya.
Toney back-heeled the Bees in front on 28 minutes and had his brace midway through the second half from the penalty spot after he was fouled by Joel Veltman.
Albion had 73% of the possession, 28 shots and forced 11 corners but Brentford came out on top in the metric that mattered.
The players showed their support for Enock Mwepu in the warm-up, wearing t-shirts with ‘Chambishi to the Premier League’ on the front' in reference to the words Enock had used when he announced that he had to retire because of a heart condition on Monday.
The Albion head coach named an unchanged 11 to the team that lost 1-0 to Tottenham last weekend.
Both teams had chances from the off as Frank Onyeka’s glancing header flew over Robert Sanchez’s crossbar before Danny Welbeck nodded a fairly tame effort at goal, which David Raya easily gathered.
Raya would need to be at his very best though to deny Albion as the game ticked into the 21st minute. Moises Caicedo’s rocket from 25-yards was tipped over by the Spaniard before he threw himself in front of Joel Veltman’s snap shot from close range.
The Bees responded and Vitaly Janelt’s cross was flicked onto Bryan Mbuemo, whose first-time effort smacked off the crossbar and away from danger.
Toney would break the deadlock with an instinctive finish. The striker smartly flicked the ball through his legs from Onyeka’s low cross – the first Brentford goal against Albion in the Premier League.
Albion tried to respond and March’s volley from Pervis Estupinan’s cross was blocked, before a coming together between Thomas Frank and Joel Veltman when the Albion defender went to pick up the ball on the side of the pitch saw the Brentford head coach and De Zerbi booked for the ensuing argument.
Hopes of an Albion comeback in the second half took a significant hit when Veltman caught the calf of Toney in the box on 67 minutes, with referee Michael Salisbury pointing to the spot. The forward continued his 100% penalty scoring record in the Premier League when he sent Sanchez the wrong way, burying it in the bottom right corner on his 100th Brentford appearance.
Raya was intent on keeping his clean sheet and his side’s two-goal cushion and he somehow kept out March’s header from close range before making another instinctive save to his left to keep out Dunk's header. In front of goal it just wasn't Albion's night.
Brentford were quite happy to sit in during the closing stages as Albion made it three without a win.
De Zerbi's men are back in action on Tuesday night, when they face Nottingham Forest at the Amex.
Albion line-up: Sanchez, Veltman, Dunk, Webster, Estupinan (Mitoma 46), Mac Allister, Caicedo, Gross (Lallana 68) March, Trossard (Undav 68), Welbeck.
Unused subs: Steele, Lamptey, Sarmiento, Enciso, Gilmour, Turns.