ALBION’S four-game winning streak came to a shuddering halt against an inspired Swansea outfit at the Liberty Stadium.
The hosts came flying out of the blocks to leave a below-par Baggies reeling at 2-0 after just 12 minutes as Wayne Routledge’s fortuitous effort quickly followed Michu’s ninth-minute opener.
And memories of last season’s three-goal drubbing on Swans soil came flooding back six minutes before the break when Routledge fired his second of the night.
Romelu Lukaku’s second goal in as many games in first-half stoppage time gave the visitors some hope.
But, despite an improved second-half display, it proved just too much of a mountain to climb for Steve Clarke’s men in their second long-distance away trip in four days.
Lukaku was handed his fourth Barclays Premier League start for the Baggies in place of Shane Long, who was among the substitutes.
Zoltan Gera missed out altogether but the Baggies were buoyed by the return of Youssouf Mulumbu from a hamstring problem as Clarke shuffled his midfield personnel.
And Jonas Olsson won his fitness race with a calf injury to maintain his ever-present league record this term.
Michael Laudrup also made two changes, with Ki Sung-Yueng and Nathan Dyer coming in for Jonathan de Guzman and Itay Shechter, who both started on the bench alongside former Baggies striker Luke Moore.
The Swans threatened as early as the second minute when Michu burst onto Pablo Hernandez’ deft chip over the Baggies backline.
The Spaniard held off Claudio Yacob before firing a fierce low shot off the base of the near post and out for a corner, although Boaz Myhill also looked to have got a vital touch with his foot.
And just seven minutes later Dyer’s deep cross from the right was played back across the six-yard box by Hernandez for Michu to open the scoring.
The Swans quickly doubled their lead within three minutes as Hernandez got to the left by-line and cut the ball back.
Olsson tried to clear but to his horror saw the ball ricochet off Routledge and into the net.
It took until the 29th minute for Albion to produce their first attempt at goal – and when it came Peter Odemwingie dragged a disappointing left-foot effort wide of the right-hand post from 25 yards.
Gareth McAuley was called into action on 35 and he did well to block Hernandez’ goalbound shot from the edge of the box after the tricky midfielder latched onto Dyer’s pull-back.
Things went from bad to worse for the Baggies six minutes before the break when full-back Ben Davies powered down the left before delivering a low cross into the penalty area, which found Routledge in acres of space – and he coolly dispatched his second goal of the night to make it 3-0.
But the visitors gave themselves a lifeline right on the stroke of half-time as Ki’s inadvertent near-post flick from Chris Brunt’s right-wing corner was volleyed in first time by Lukaku from ten yards.
Clarke switched to a 4-4-2 formation for the second half, with Odemwingie pushing up alongside Lukaku and James Morrison moving to the right wing.
And the Baggies instantly looked brighter with Lukaku latching onto McAuley’s ball over the top, only to volley horribly wide from 15 yards under pressure from Chico Flores.
Referee Lee Mason waved away Swans’ appeals for handball against Olsson in the penalty area on 53 after Routledge’s cross-cum-shot struck the Sweden international at point-blank range.
After that Albion began to gather some momentum and just before the hour-mark Ashley Williams had to be alert to stop Odemwingie getting on the end of Lukaku’s curling left-wing cross to the near post.
Laudrup made the first change of the night in the 64th minute as Moore came on for Dyer.
Michu almost doubled his tally for the night on 71 – but saw his bullet header from Hernandez’ cross flash just past the right-hand post.
The Swans hotshot was at it again three minutes later as he forced Myhill to swoop low to his left and push the ball away.
Ki then curled a superb 30-yard free-kick a fraction past the upright and into the side netting.
And in the end the South Wales side comfortably saw their way to three points as they stretched their unbeaten run to five games.
SWANSEA (4-5-1): Tremmel; Rangel, Chico, Williams (c), Davies; Britton, Ki, Dyer (Moore 64), Hernandez (de Guzman 74), Routledge; Michu (Agustien 86). Subs not used: Cornell (gk), Monk, Tiendalli, Shechter.
ALBION (4-2-3-1): Myhill; Jones, McAuley, Olsson, Ridgewell; Yacob, Mulumbu; Odemwingie, Morrison, Brunt; Lukaku. Subs not used: L Daniels (gk); Popov, Rosenberg, Long, Fortune, Tamas, Dorrans.
GOALS: SWANSEA – Michu (9), Routledge (12&39); ALBION – Lukaku (45+3).
BOOKINGS: ALBION – McAuley (foul 13), Brunt (foul 45), Olsson (dissent 52), Jones (foul 90+3).
REFEREE: L Mason (Lancashire).
ALBION STARMAN: James Morrison.