Chelsea 2-0 West Bromwich Albion

Diego Costa has scored 11 goals in the league this season

• West Brom's Yacob receives straight red card

• Chelsea 12 unbeaten at start of the season, a club record

• Mourinho's 50th Premier League game in second spell

• Costa and Fabregas both start for Chelsea after injury

Chelsea opened up a seven-point lead at the Premier League summit as goals from Diego Costa and Eden Hazard secured a one-sided win over 10-man West Brom.

Costa's chest down and volley got the ball rolling for Jose Mourinho's side.

Hazard was then gifted a cheap second after 25 minutes, firing home after West Brom switched off at a corner.

Claudio Yacob's two-footed lunge on Costa earned him a straight red card from Lee Mason, effectively ending the contest inside half an hour.

West Brom were spared further pain but it was nevertheless a chastening loss for the visitors, who were second best by a considerable margin in all areas.

Chelsea almost went ahead inside five minutes when Hazard's low cross was turned goalwards by John Terry but Ben Foster got down to divert the ball away.

West Brom's plans for Costa looked clear early on when three defenders crowded him out in the area, but he escaped their attentions to devastating effect on 11 minutes.

Oscar's delivery from the left picked out the striker, who was given the benefit of a narrow offside call before controlling on his chest and firing his 11th goal of the season beyond the exposed Foster.

Oscar nearly doubled the lead when his sliced drive brought a diving save from Foster, who did even better to deflect away the rebound from the onrushing Costa.

Costa then guided Branislav Ivanovic's inviting centre millimetres wide, as the contest, barely 20 minutes old, grew ever more one-sided.

In what was the Blues' first home game since Jose Mourinho criticised the atmosphere at Stamford Bridge, Chelsea's performance was greeted enthusiastically by the fans.

They had another goal to cheer on 25 minutes, the West Brom defence dozing at a corner and allowing Cesc Fabregas to deliver short and low to Hazard, who drifted away from Craig Gardner's half-hearted challenge before firing an untidy deflected finish through Foster.

Five minutes later, the writing was on the wall for Alan Irvine's rattled visitors as Yacob, making his first league start of the season, was sent off for a wild tackle on Costa.

West Brom made it to the break without further punishment but within moments of the restart were exposed again as Nemanja Matic volleyed over Oscar 's lofted ball.

For all their dominance, Chelsea could not make any further inroads after break, but it was all a far cry from events in this same fixture a year ago, when Albion were seconds away from inflicting Mourinho's first ever league defeat at Stamford Bridge.

West Brom boss Alan Irvine: "We had a game plan that was made more difficult by the first goal, which I think was offside. But the second one I was disappointed about - we pride ourselves on being organised at set-pieces and we weren't as organised as we should have been."

On Yacob's dismissal: "I can see why he sent him off. I don't think Claudio was trying to do any damage - he was trying to win the ball - but the rules are such that if your feet leave the ground with both feet you're not in control."

Claudio Yacob was making his first league start of the season

Albion goalkeeper Ben Foster was busy throughout as Chelsea racked up 21 shots on goal

Saido Berahino, fresh from his England call-up, endured a frustrating afternoon for West Brom

Eden Hazard's goal was his fourth in the league this season

West Brom have now won just three of their last 15 Premier League games, eight of those defeats