© PA Photos
Despite an off-key display in the first half, the hosts went ahead in the 36th minute when Mata linked up with Ramires before seeing his shot creep in at the near post.
However, Steaua grabbed an away goal moments before the break as Vlad Chiriches pounced in the area following a corner.
© AP Photos
Chelsea regained the lead on the night with an hour played through Terry's header from a Mata free kick, and it was 3-1 when Torres fired into the bottom corner with 20 minutes left on the clock.
Torres had the chance the get on the scoresheet again late on, but the striker's penalty hit the crossbar following a foul on Eden Hazard.