Robin van Persie criticised some of his Manchester United team-mates for "sometimes occupying the spaces I want to play in" following their wretched 2-0 defeat to Olympiakos in the Champions League last-16 opening leg at the Karaiskakis Stadium on Tuesday night.

The Dutchman's voicing of disquiet at the dismal campaign echoes Rio Ferdinand's comments earlier in the season, when the defender questioned the manager David Moyes' approach of naming the side close to kick-off.

Van Persie told the Dutch TV channel NOS: "Our fellow players are sometimes occupying the spaces I want to play in. And when I see that it makes it difficult for me to come to those spaces as well. So that forces me to adjust my runs, based on the position of my fellow players. And unfortunately, they're often playing in my zones. I think that's a shame."

The striker, who missed a good chance towards the end of the game, defended Moyes, however. "He's working hard at it, and so are we. Sometimes we play well, but not all the time. We don't have luck on our side. It's easy to point the finger at someone, but I'm not like that. We have to do better ourselves."

Of his missed chance, Van Persie said: "I rushed that shot. That's a shame because I don't get a lot of chances so when you get one, you have to score."

Moyes, who was unaware of the comments when he did his post-match press conference, admitted that he did not see the "level of performance coming" in the defeat, which the manager branded their poorest in Europe under him.

Goals from Alejandro Domínguez and Joel Campbell allowed the unfancied Greek champions to hand United a first loss in the Champions League since Moyes became the manager.

He said: "That's the worst we have played in Europe, that's for sure. It was a really poor performance. We never really got going from the start and we didn't deserve anything because of the way we played. We never really got to grips with things and to a man you could hardly pick anybody out. We just didn't perform."

Moyes refused to criticise his players, though he did admit to concern at what he had seen. "We came into the game in good form and a good mind-set but it just didn't show. I am just surprised. I didn't see that level of performance coming. I just didn't see it. But I have to say I still don't think we were necessarily two goals worse off. But we didn't offer enough to create a goal. I expected Olympiakos's performance," said the Scot before explaining why he had gone on to the pitch at the end to speak to a match official.

"We showed fair play when the player got injured and Danny Welbeck kicked it back to the goalkeeper so I would have expected fair play from the referee when the cross came in the last minute. I would have expected the same from the referee."

Pressed that Moyes must be disappointed at players who he is showing faith in, the manager said: "I take responsibility. It is my time and I will always front up. We didn't play well. We have to play better. We can do and the one good thing is that there is still a second game to come. We will do everything we can possibly do to reverse the 2-0 defeat."

Moyes left Adnan Januzaj out of the match-day 18 despite the teenager impressing throughout the season. To explain, he said: "I decided last week I would play Tom Cleverley so I chose not to use him."

Roy Keane, working on ITV as a pundit, was highly critical of the display. The former United captain said: "Nobody predicted that. It's been a tough night for the club, the players and the fans. There is a lack of confidence and there are some players who just don't have the quality. They need six or seven players to rebuild the club. Privately, David Moyes will be shocked at the quality he is working with."

When this last claim was put to the Scot, he said: "I think there is undoubtedly talent at Manchester United but tonight we didn't show it. Me and the team we didn't show it together. It is something we will have to do. We will put it right. We are determined to put it right and will have opportunities to do that in the coming weeks.

"The players are hurting as well. They know how they performed. But it is a team here and it won't change. We will stick to together. There is a second game to come and Old Trafford has seen some great nights in the past and I am looking forward to hopefully seeing another one."

With United having failed to claim an invaluable away goal they have to win by a margin of three in the return leg at Old Trafford on 19 March. Michael Carrick, moreover, insisted that United can still go through to the quarter-finals. "We feel like we are still in with a chance going back to Old Trafford. We've lost a game. We came here hoping to win but we are not out of the tie. You're looking for me to blame someone but everyone at the club is judged by results."

That brought more criticism from Keane. "That interview was just like the performance: flat. He should say a bit more, have a bit more urgency even in his interview. That just reflected United's performance tonight: flat, with no urgency."

The sense of disarray at the club was heightened when Carrick's wife responded by branding Keane a "****" in a tweet. It read: "Roy Keane what a ****, says anything to provoke a reaction.. That's all.. Done..." She subsequently tweeted: "Deleted my tweet .. Emotions got the better of me .. Just disappointed."