Steaua Bucuresti have beaten European champions Chelsea 1-0 in the first leg of the sides' Europa League last-16 tie.

The Romanian league leaders broke the deadlock on 34 minutes with a controversial penalty kick.

Ryan Bertrand had his arm on Raul Rusescu's shoulder and was adjudged to have fouled the Steaua forward, who emphatically converted the resultant spot kick.

Rusescu's successful effort was the game's first shot on target.

Branislav Ivanovic had earlier headed over the bar from close range.

Chelsea twice came close to levelling the game late in the opening period, but goalkeeper Ciprian Tatarusanu made two smart saves to deny Yossi Benayoun and then Fernando Torres.

The hosts continued to frustrate Chelsea after the break.

Marko Marin was the only visiting player to come close to an equaliser in the second half.

The substitute forced a decent parry out of Tatarusanu, after beating two players on a jinking run.

Stamford Bridge will host the second leg a week tonight.