Inter Milan?s Adriano (left) in a tussle with FC Porto?s Pedro Emanuel (right) and Ricardo Costa during their Champions League match in Porto on Wednesday. (AP)

London: Barcelona capitalised on a sending off to beat Chelsea while AC Milan took advantage of a goalkeeping error to win at Manchester United on a disappointing night for English clubs in the Champions League.

Olympique Lyon won 3-0 away against Werder Bremen on the second night of matches in the first knockout round but holders Porto had to settle for a draw at home to Inter Milan and will struggle to hold on to their title in next month?s second leg.

The place to be for controversy on Wednesday was the Nou Camp where Barcelona battled back from a goal down to win 2-1 after Chelsea?s Ivory Coast striker Didier Drogba was sent off 11 minutes into the second half for a second yellow card.

The big-spending London side were up against it for most of the first period but went ahead when Barcelona full back Juliano Belletti put the ball into his own net after Damien Duff charged down the right and cut a cross back into the box.

Chelsea?s defence held firm as the Spanish side pushed forward looking for an equaliser but the match turned against the visitors when Drogba, who has only just returned from injury, was dismissed after barging into keeper Victor Valdes.

The Spanish league leaders took full advantage against their English counterparts just 11 minutes later when substitute Maxi Lopez fired past goalkeeper Petr Cech into the far corner.

Chelsea now had to defend desperately but there was nothing they could do when African Player of the Year Samuel Eto?o burst between two defenders to fire home a precise pass from Lopez with 17 minutes of a pulsating match remaining.

It was the first time under Mourinho that Chelsea have lost two games in a row, after a 0-1 defeat by Newcastle United in the FA Cup last Sunday, but the Portuguese coach will just be thankful they have an away goal to take into the second leg.

However, Mourinho refused to talk to reporters after the match following a reported incident in the tunnel at halftime and Chelsea said they will be filing an official report with Uefa.

A tight game at Old Trafford, won 1-0 by Milan, was decided by a goal from Hernan Crespo, clearly enjoying himself on loan with the Italians after a disappointing season at Chelsea, but he was given a lot of help by United goalkeeper Roy Carroll.

The Argentine striker scored in the 78th minute after Carroll spilled Clarence Seedorf?s long range effort to give Milan their first competitive win on English soil.

United manager Alex Ferguson sent on Dutch striker Ruud van Nistelrooy with 30 minutes left for his first appearance in three months after injury but the home side failed to break down a tough Milan defence and must now win in Milan on March 8.

Milan clearly enjoy playing at Old Trafford ? where they won the 2003 Champions League final ? but for United it was a first home defeat in the meet for 21 matches.

Lyon ran out comfortable winners over Werder Bremen after a first-half goal by Sylvain Wiltord was followed by strikes from Mahamadou Diarra and Juninho Pernambucano to take the French side to the brink of the quarter-finals.

Holders Porto have it all to do after a 1-1 draw with Inter Milan who went ahead in the 24th minute through Obafemi Martins before the Portuguese side equalised just after the hour thanks to a strike from central defender Ricardo Costa.

Porto had chances to win and bring to an end Inter?s unbeaten run, now 38 games in domestic and European competition this season, but the Milan side almost snatched victory as Christian Vieri and Stankovic came close.