ATHENS — Manchester United's dwindling hopes of lifting a trophy this season are dangling by a thread after it produced an abject display to lose 2-0 at Olympiakos Piraeus in a Champions League last-16 first leg Tuesday. Alejandro Dominguez opened the scoring with a clever first-half flick and Arsenal loanee Joel Campbell added a sublime second goal to leave United facing a huge task to overturn the deficit in the return match at Old Trafford on March 19. “That's the worst we've played in Europe. We didn't deserve to get anything,” manager David Moyes told reporters. “I'm surprised, I didn't see that level of performance coming. “I take responsibility, we have to play better. The players are hurting.” Defeat at the Georgios Karaiskakis Stadium represented yet another body blow in an inauspicious campaign for last season's English Premier League title winner. United is out of the FA Cup and the League Cup and trails Premier League leader Chelsea by 15 points with 11 games left to play. Moyes' men looked sluggish and disjointed against an inexperienced Olympiakos side bidding to reach the quarterfinals for only the second time in its history. It was the first time the Greeks had beaten United in five attempts. “To beat a great side like United, the way we did, is something very special and I can't hide the joy and pride I feel for my players,” said Olympiakos coach Michel. “We picked the best moment to show Greek football is alive and kicking,” added the former Spain and Real Madrid striker. Moyes opted to start with two wingers, Antonio Valencia and Ashley Young, but neither made an impact in a first half in which runaway the Greek league leader displayed real energy and hunger. Dortmund hits top gear Coach Jurgen Klopp said Borussia Dortmund had produced a near-perfect performance to leave it on the verge of the Champions League's quarterfinals after routing Zenit St Petersburg away also Tuesday. Poland striker Robert Lewandowski scored twice as Dortmund romped to a 4-2 win at Zenit's Petrovsky Stadium in the last 16, first-leg clash. Klopp was delighted as Borussia bounced back from Saturday's shock 3-0 defeat at relegation-threatened Hamburg in the Bundesliga to dominate Zenit. Last season's finalist raced into a 2-0 lead with goals by Henrikh Mkhitaryan and Marco Reus inside the first five minutes to leave the Russians reeling. The host pulled two goals back after the break as central midfielder Oleg Shatov scored, then Brazil's Hulk converted a penalty. But on both occasions Dortmund responded almost immediately as Lewandowski scored twice to give the German side a huge advantage ahead of the second leg next month. “That was close to an optimal performance,” said Klopp. “In terms of pressing and counter pressing, that was a copybook performance from us against a dangerous team. “We were incredibly active and aggressive. “It's not easy to do that and the team put in a fantastic performance.” But Klopp urged caution ahead of the return leg on March 19 by insisting nothing has been decided yet. — Agencies