Blackburn manager Mark Hughes warned his side are too easy to beat after succumbing to a second successive 4-0 Premiership defeat.
Rovers were outplayed throughout as Eidur Gudjohnsen hit home a hat-trick.
And Hughes said: "We have a problem defensively and need to be more resolute. The goals against column doesn't lie.
"We have to get back and make sure we're more difficult to beat. At the moment we're too easy to beat."
Blackburn had held Chelsea well before Gudjohnsen found the net twice in the space of two minutes towards the end of the first half.
After that, Rovers capitulated and Hughes said: "We never really had a foothold in the game after the second goal."