ALEX FERGUSON and his players arrived in London last night with encouraging news about Nemanja Vidic's fitness ahead of a game against Chelsea that could effectively seal Manchester United's 17th championship.

Vidic missed the first leg of the Champions League semi-final against Barcelona on Wednesday after going down with a stomach bug that was serious enough for him to be taken to hospital on the evening before the match.

He was too ill to attend the scoreless draw at Camp Nou, but he reported feeling much better yesterday, and it is understood he did some light fitness work before the team flew back to England.

He has been placed on a special programme of fluids and medication, and United's doctors have told Ferguson they are optimistic about the player's chances of being available for the game at Stamford Bridge tomorrow.

That would mean Ferguson reverting to his usual defence, with Wes Brown moving across to right-back in place of Owen Hargreaves.

Yet Ferguson will almost certainly make other changes. Park Ji-sung failed to make any positive impact when he was preferred ahead of Ryan Giggs in Barcelona and was one of the players to whom Ferguson was referring when he complained about the team's inability to keep possession for longer periods.

Ferguson identified Paul Scholes as "the one player" who had followed his pre-match instructions to treasure the ball, but that in itself presents the manager with problems. If he wants Scholes to be fresh for the second leg at Old Trafford on Tuesday, he might feel inclined to rest him at Stamford Bridge, with Anderson promoted to the side.

About the only certainty is that if United get a penalty Cristiano Ronaldo will not hand over the responsibility: the team's leading scorer made it clear he believes his miss against Barcelona was merely a one-off.

"It's not a problem for me," he said. "I'm always confident. I've 38 goals this season so it's not a problem if I miss one or two. I've scored 16 or 17 penalties since joining United and I've missed only two. That's a good record."

Nonetheless, his miss threatens United's route to the final, and Pepe Reina, the Liverpool goalkeeper, suggested yesterday that Ronaldo should have stuck to what he knows best rather than change his style.

Reina, who began his career at Barcelona and has developed a reputation as a specialist penalty stopper who studies his rivals closely, said: "Ronaldo always goes left from the penalty spot, his penalties are invariably low and left. Even against Arsenal the other day, when he was made to take the penalty again, he still went low and left on both attempts - and scored them. Against Barcelona he tried to surprise them, he changed his style and got it wrong."

Chelsea have rarely been far from adversity this season but yesterday their previous difficulties paled into insignificance when Frank Lampard's mother, Pat, lost her battle for life, having been in the grip of pneumonia for the past 11 days. She was 58.

Lampard has not wanted for support from his team-mates and as he took time to grieve with his family they communicated their best wishes.

Lampard is not expected to play against Manchester United, while it remains to be seen whether he features in the Champions League semi-final second leg against Liverpool at Stamford Bridge next Wednesday.

Avram Grant, the manager, had remarked that some matters in life were far more important than football, and Lampard will be granted compassion and all the time that he needs.

The club have begun to confront the question of how to move on. The next six days will further shape their season, and the prospect of a silver-lined finish is real.

Victory over United would move Chelsea to level on points, if not goal difference, with the champions at the top of the Premier League table, while they hold the upper hand over Liverpool after the 1-1 draw in the first leg.

It is too glib to suggest that the players will want to do it for Lampard in his absence. Yet tragedy can have a bonding effect in professional sport and the team's fighting spirit will not be knocked.

It is what Michael Ballack believes has served to keep Chelsea in contention for the biggest prizes and it will have a significant part to play against United and Liverpool.

"When you look back on this season, we have been through a lot of difficult situations," said Ballack. "We have had a lot of bad injuries and lost some important players to the African Cup of Nations. But we are still in a good position in the Premier League and we are in the semi-finals of the Champions League, so that shows how strong we are as a team."