The defeat will increase the pressure on Manchester United’s embattled coach David Moyes, who said: "’That’s the worst we’ve played in Europe, we didn’t deserve to get anything.''

Manchester United’s Champions League future is in doubt after a 2—0 meltdown on Tuesday at Greek champions Olympiakos, in a tense round of 16 first leg game.

Earlier on Tuesday, last season’s runners-up Borussia Dortmund enjoyed a 4—2 romp at Zenit Saint Petersburg, with Robert Lewandowski banging in a brace.

United enjoyed 54 per cent possession in Piraeus but failed to translate that into many clear goal chances. Olympiakos, meanwhile, were content to soak up the pressure and play on the break, especially after Alejandro Dominguez gave them the lead in the 38th minute.

That goal came after United’s Patrice Evra made a poor clearance, allowing local captain Giannis Maniatis to try a long shot, which was deflected in by Dominguez with a clever flick.

Things went from bad to worse for United in the 54th minute when Joel Campbell — on loan from Arsenal — made it 2—0 with a blistering left-foot drive, after cheekily playing the ball through the legs of Michael Carrick.

United’s only clear chance fell to Robin Van Persie, who wastefully blasted over the crossbar to the relief of the noisy Olympiakos fans.

The defeat will increase the pressure on United’s embattled coach David Moyes, who said: “’That’s the worst we’ve played in Europe, we didn’t deserve to get anything.

“I’m surprised, I didn’t see that level of performance coming. I take responsibility, we have to play better. The players are hurting after that.” Meanwhile, veteran Carrick said: “It’s a disappointing night. We feel like we are still in with a chance going back to Old Trafford. We came here hoping to win but we are not out of the tie.” “We had good possession in the first half without penetrating through their lines but at the same time they didn’t cause us any problems.

“We didn’t start the second half well and that put us on the back foot. We are not getting results and as players we have to take that on the chin.” Olympiakos’ Spanish coach Michel said: “This is a wonderful result for us, but it does not surprise me at all. The team has been in good form for a long time now, and I knew we could win tonight.

“I’m sure the second leg will be difficult, because Old Trafford is an incredible stadium. But I am convinced that we have the quality and personality to do well there.”

Earlier in Saint Petersburg, Zenit were torn apart by an ambitious Dortmund side keen to show that reaching the final last season was no fluke.

“We showed great character tonight. But the tie is not over yet, and we will have to work very hard and be very attentive in the second leg,” said Dortmund coach Juergen Klopp.

Meanwhile, his veteran midfielder Sebastian Kehl said: “We made a great start, with two early goals, and that really helped to put us in control.” Dortmund started out full of fire and purpose, and Henrikh Mkhitaryan shot them ahead after just four minutes following a penetrating run by Marcio Reus.

Zenit were in a state of shock, and Reus made it 2—0 two minutes later after being set up by Lewandowski.

In the 58th minute Oleg Shatov pulled a goal back for Zenit following a clever move between South Americans Hulk and Salomon Rondon.

However, Lewandowski quickly made it 3—1 to the visitors.

Hulk scored a second consolation goal for the hosts after Viktor Fayzulin was pulled down, only for Lewandowski to make it 4—2 after being set up by the impressive Reus.

A disappointed Rondon said: “Conceding two goals so early in the game was terrible for us. We did our best to recover but it was not easy.

“Even so, I still think we have a chance in Dortmund. We’ll just have to go there and do the very best we can.” The second legs will be played March 19.

Wednesday will see 2012 champions Chelsea visit Galatasaray and Schalke 04 at home to Real Madrid.

More In: Sport | Football