The England defender was chasing a ball towards the left touchline in the 58th minute at Stamford Bridge when his left knee appeared to buckle beneath him and he fell to the turf with no other player in sight.

Cole was just beginning to find form for the first time since his controversial transfer from Arsenal last summer.

Manager Jose Mourinho was also just preparing to welcome back captain and central defender John Terry after a month on the sidelines. Chelsea have also suffered recent injuries to Terry's centreback partner Ricardo Carvalho and midfielder Joe Cole.

Mourinho will make noises that his squad will not be able to cope with another loss, but Wayne Bridge appears set to have a spell in which to prove himself as more than just an able deputy to his long-time England rival.

On the pitch, it was perhaps too much for Chelsea to hope that a victory would help them cut into Manchester United's six-point lead, but the Blues did at least manage to record another dull but effective victory against mid-table opposition.

It was a miserable night for Andriy Shevchenko, who missed three good chances to score, but Didier Drogba maintained his remarkable consistency with another goal which saw him increase his tally to 23 in all competitions.

In the sixth minute Frank Lampard picked up a loose ball in the centre circle and released Drogba with a perfectly weighted pass.

The former Marseille striker outpaced Stephane Henchoz and put the ball wide of Brad Friedel and inside the far post for the opener.

Blackburn manager Mark Hughes, himself a former Stamford Bridge favourite in the twilight of his stellar career, was left stunned as his side had made an encouraging start.

Matt Derbyshire missed their best chance just before the break and when Chelsea re-emerged after the interval they gave a glimpse of their ruthless streak, so evident on their own turf in recent seasons, by adding a further two goals.

Lampard, one of Chelsea's most reliable performers, was on hand in the 66th minute to hit a superb strike to make it two.

Jon Obi Mikel drifted in from the left and played the ball to Lampard, who advanced a few yards before unleashing a vicious, swerving effort which beat Friedel and found its way into the roof of the net.

Chelsea were then able to enter their comfort zone, but to their credit they decided not to and it was no surprise when they scored a third in stoppage time.

Substitute Saloman Kalou -- a summer signing recently criticised by Mourinho -- found himself free on the left side of the penalty area and he easily beat Friedel with a side-footed effort.