After a dazzling display to reach the Champions League quarter-finals against Barcelona, the Blues trudged on towards the domestic title thanks to a 26th-minute Didier Drogba strike.

Second-placed Manchester United already admitted they had a mountain to climb to overhaul the leaders and Chelsea did enough to make the summit even further from their grasp with just nine games remaining.

West Brom have their own hill to overcome, the defeat keeping them five points from safety.

Ivory Coast striker Drogba missed the thrilling 4-2 victory over Barcelona here having been suspended for his dismissal in the first leg but was reinstated by coach Jose Mourinho.

The Blues dominated possession with man-of-the-match Joe Cole sending a string of inviting crosses into the box.

Drogba had fluffed a chance to chip Albion goalkeeper Russell Hoult when clean through but he made no mistake for his goal.

Frank Lampard played a through-ball on the turn for left-winger Duff who charged into the box and squared first-time for the unmarked Drogba, the hitman side-footing the ball in from eight yards.