United ended Arsenal's hopes of a treble on Saturday when Paul Scholes's first-half goal gave them a 1-0 victory over the holders in a tense FA Cup semi-final at Villa Park.

Arsenal, whose premier league lead was cut to four points after Chelsea won 1-0 at Spurs, have only three days to recover before the Champions League showdown with Chelsea at Highbury.

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Chelsea have not beaten Arsenal in their last 17 meetings and Wenger's team will start firm favourites after the first leg finished 1-1 but Ferguson told reporters: "I think it will be a difficult game on Tuesday night."

"I think (Chelsea head coach Claudio) Ranieri is due luck, (after) the season he's had, the pressure he's been under."

"I think it's a difficult game for them (Arsenal). I think they will win the league, I'm sure of that. They should not throw that away, that's a great position they are in there."

"But I wouldn't bet on them on Tuesday night. It's a difficult game. It's not an easy one."

REYES OUT

Arsenal manager Arsene Wenger was angry at some of United's tackling in Saturday's game which left Spanish striker Jose Antonio Reyes facing three weeks out due to knee ligament damage and Swedish midfielder Freddie Ljungberg nursing a broken hand.

Arsenal, who are unbeaten in a record 30 league games since the start of the season, are in the middle of a run of four games in nine days that could dramatically alter the outcome of their season.

After the Chelsea game they host Liverpool in the premier league on Friday and travel to Newcastle on Sunday and Wenger is suddenly fighting to prevent the wheels falling off the London club's season.

He is sure to start with striker Thierry Henry against Chelsea after his gamble of leaving the French dangerman on the bench until the 58th-minute of Saturday's game backfired.

Reyes's absence means Dennis Bergkamp will almost certainly start alongside Henry.

"It was big blow not only to lose but to lose players," Wenger said after seeing his side's bid to win a third successive FA Cup go up in smoke.

"Man United fought hard. They defended every ball but some tackles were really on the limit."

"Our priority is the championship and the Champions League but when you are in the semi-final of the FA Cup you want to win it."

Manchester United are firm favourites to lift the FA Cup on May 22 when they meet first division Millwall or Sunderland, who play their semi-final later on Sunday.