Sir Alex Ferguson defended Manchester United's young players last night, saying they were not to blame for their humiliating exit from the Champions League, though the defender Patrice Evra said the club had been unprofessional in Europe and described dropping into the Europa League as an "embarrassment".

United had only to avoid defeat against Basel to qualify for the knockout phase of a competition in which they have reached the final three times in four seasons. A 2-1 defeat at St Jakob-Park condemned the Premier League champions to a third group exit in 17 Champions League seasons and produced a scathing reaction from United players past and present. The former United captain Roy Keane, in Basel as part of ITV's commentary team, said his old club had "got what they deserved" from a campaign that saw Ferguson's team fail to beat Basel or Benfica and take maximum points only from the Group C whipping boys, Otelul Galati.

"Of course we are disappointed, it is the only way we can feel," Ferguson said. "We had so much possession of the ball and so many good opportunities in the last third of the field but in the finishing part we let ourselves down."

Keane blamed United's early exit on the latest group of young players that Ferguson has introduced to the club. He said: "People have talked about the young players – you've had Jones, Smalling, Young coming in, everybody building them up, but they've got a lot to do, it's a reality check for some. I'd be getting hold of some of those lads, saying, 'You'd better buck up your ideas.' I think their best player tonight was Ryan Giggs. That sums it up – he's 37 or 38, you can't be depending on him."

Ferguson responded angrily when Keane's comments were relayed to him after the game, and made reference to his former midfielder's failure in management at Sunderland and Ipswich Town.

The United manager said: "I don't know why you are bringing this up from a television critic. Roy had an opportunity to prove himself as a manager and it's a hard job. We have enough good young players to see us through. I have every confidence in them. That is part of football. You have to deal with disappointment. It has been used as motivation at this club many times before. These young players will have to cope with it and get on with it in their careers."

United's Champions League status was not the only thing they lost. The defender Nemanja Vidic suffered what seemed to be a serious knee injury after an accidental tangle with Marco Streller, who gave Basel an early lead following a mistake by David de Gea. "We don't know the extent of it at this moment in time," said Ferguson. "We think it is a medial ligament and hopefully that is the worst of it."

The United manager also lamented the impact of Europa League football on the team's prospects of overhauling Manchester City in the Premier League. He said: "It is a competition we have never been in before. It does mean Thursday and Sundays throughout and that has to be dealt with. It is not the best but that is our penalty for not qualifying."

Ferguson said that United had gone out of the "best tournament in the world" as a consequence of a complacent performance against Basel at Old Trafford. "We were careless in that first game – we let ourselves down badly then. That has cost us," he said.

Evra, however, went much further, saying that last season's runners-up had not performed throughout this season's Champions League. The France defender said: "Today is a really sad day not just for the players but for the staff and the fans, but we are Manchester United and next year we won't throw it away again. We still have things to win this season and we have to make sure we do that.

"We need to play with the heart and the fans deserve more than us throwing it away. We have to be honest and say we haven't been professional from the beginning of this competition. I don't know why. Maybe one or two of us have to look in the mirror and say we can do a lot better than we have done."

Evra also said that it would be difficult to adjust to the reality of life among European football's second tier. The left-back said: "I'll be honest with you, the way I fell now it is Champions League or nothing but when we start playing in the Europa League we will try to win it.

"But of course I play for Manchester United to play in the Champions League. I am not ready for it because it is a new experience. Even if it is [a] friendly, when I pull on United shirt I do my best to win that trophy. But it is embarrassing to be in the Europa League."