Playing hours after sacking Nicolas Anelka following his five-match ban for performing a 'quenelle' salute, West Brom fell behind to a second-minute strike by Roland Lamah at the Liberty Stadium.

However, Stephane Sessegnon marked his first start since New Year's Day by equalising early in the second period before Mulumbu completed the visitors' comeback with an elegant finish.

The Congolese midfielder's goal gave West Brom manager Pepe Mel a first victory at the ninth attempt, lifting the club three points clear of third-bottom Sunderland and to within one point of 14th-place Swansea.

West Brom sacked Anelka late on Friday after he claimed to have unilaterally terminated his contract and the French striker's departure should allow the club to focus purely on their bid to avoid the drop.

Mel brought Sessegnon, James Morrison, Graham Dorrans and Craig Dawson into his starting XI, switching to a 3-5-2 formation, but he saw his side fall behind with less than 120 seconds on the clock.

Wilfried Bony's pass from deep split the visiting defence and Lamah cut in from the left before beating Ben Foster from a prohibitive angle.

In response, Victor Anichebe shot straight at Swansea goalkeeper Michel Vorm, but the hosts, characteristically dominating possession, continued to threaten.

Foster thwarted Bony at point-blank range after the Ivorian attacked a cross from Lamah, who put a header off-target from a corner and narrowly failed to apply the finishing touch to a centre from Wayne Routledge.

Routledge then teed up Bony to lash a shot over the top, before the livewire Lamah sent in a cross that eluded Bony and could not be turned in by Jonathan De Guzman.

Swansea captain Ashley Williams, meanwhile, could only direct a free header into the ground and over the bar from eight yards out.

West Brom attacked the second period with vigour, equalising in the 52nd minute when Sessegnon sent a low shot skidding past Vorm from 25 yards.

Swansea had a penalty appeal turned down after a shot from Bony appeared to strike Gareth McAuley on the arm and the hosts then introduced Michu from the bench, following a three-month absence with an ankle problem.

De Guzman forced Foster to save with his feet after a driving run and with five minutes remaining, Mulumbu guided a shot between Jordi Amat's legs and past a motionless Vorm to give West Brom a much-needed victory.