Romelu Lukaku scored two more goals as Albion claimed a deserved win against Sunderland to reach the 40-point mark.
The Baggies’ on-loan leading scorer capped a fine display with his 11th and 12th goals of the season to give his side a second successive win.
The Chelsea teenager netted a penalty before half-time and a bizarre second goal with 15 minutes to go.
But Albion had to withstand some late pressure from the Black Cats, who pulled a goal back with 10 minutes remaining through Stephane Sessegnon.
The game also saw rebel striker Peter Odemwingie make his first appearance since his January fall-out with the club, joining the game as a late substitute to loud boos from many fans.
The first 25 minutes were largely uneventful but the game exploded into life just before the half-hour.
First Liam Ridgewell found space on the left and crossed for Lukaku, who sent a header wide.
And the visitors went even closer when former Wolves man Steven Fletcher hit the base of Ben Foster’s right-hand post with a shot on the turn from the edge of the box.
Adam Johnson charged down Steven Reid’s clearance and, when the ball dropped to Danny Graham, the Sunderland striker had his shot saved by Foster.
Moments later Lukaku combined well with James Morrison on the right and the Scotland international delivered an inviting cross that narrowly evaded the onrushing Shane Long.
Albion then took control and should have been ahead when Ridgewell delivered another excellent cross after an overlapping run and found an unmarked Youssouf Mulumbu, who headed wide when he should have scored.
There was controversy on 30 minutes when referee Roger East disallowed a Lukaku ‘goal’ after he seized on a prodded pass by Morrison and beat Simon Mignolet.
The crowd celebrated but the official had already blown for a foul on Morrison.
However, he made amends moments later when he awarded Albion a crucial penalty.
Ridgewell was again the instigator as his cross was handled by former team-mate Craig Gardner, with Lukaku driving a low shot past Belgium international colleague Mignolet.
And it could have got better for the Baggies just before the break when Morrison crossed for Shane Long, who headed wide.
Sunderland made a bright start to the second half and could have equalised early on when a Seb Larsson corner found Sessegnon beyond the far post.
But he saw his shot cleared off the line by Mulumbu.
The Baggies then regained their advantage and Lukaku twice had shots beaten away by Mignolet.
Albion applied more pressure but had to wait until the 75th minute to double their lead.
Lukaku burst away from John O’Shea out wide on the halfway line and Titus Bramble’s attempted backpass was too short for MIgnolet.
The keeper beat Lukaku to the ball but his clearance hit Lukaku and flew like an arrow into the net.
But it was 2-1 moments later as the Baggies failed to clear their lines and Sessegnon curled a shot past Foster.
In the closing stages Odemwingie replaced Lukaku, with the two-goal hero receiving a standing ovation while his replacement got loud boos and abuse from a large number of fans.
But with his first touch the Nigerian cut inside and fired a cross-shot just wide.
Foster had to make a timely save from Vaughan in the closing moments as the Baggies held on to win.
By Steve Madeley