SIR ALEX Ferguson fears Manchester United could be in for a difficult ride at Ewood Park tonight if Brad Friedel reproduces the kind of mesmerising form he showed in last week's Carling Cup semi-final tie at Old Trafford.

The former United States international pulled off a string of breathtaking saves before United finally beat Rovers 2-1 on the night and 3-2 on aggregate.

Nevertheless, Friedel not only saved a first half penalty from Ruud van Nistelrooy, he also thwarted the Dutchman on two more occasions - the first of which was reminiscent of Gordon Banks' jaw-dropping effort to deny Pele in the 1970 World Cup.

It's not the first time the American has played out of his skin against the Reds - in fact, Ferguson claimed Friedel must have made at least 40 saves' in recent clashes between the two sides.

Now the United chief is worried another inspired performance from the 34-year-old could scupper the Reds' chances of securing a first Premiership win in three years at Ewood.

"We had to battle for a result," said Fergie, referring to last week's semi-final second leg.

"Their goalkeeper had another fantastic night and if he has a similar night to what he normally does against us, it's going to be a very tight game."

With Alan Smith suspended, Ferguson faces another selection dilemma in midfield, an area which has caused him no end of headaches this season, particularly since Roy Keane's shock departure.

Cristiano Ronaldo and Ji-sung Park are both available again following suspension and injury respectively, which will give the United boss some extra options, but he is not ruling out the possibility of sticking with the strike trio of Ruud van Nistelrooy, Wayne Rooney and Louis Saha, who all started last week's second leg.

"It's certainly an option to play the three of them," said Ferguson.

"I don't think the system worked in the first half against Blackburn, but once we moved Saha towards the left, we got a better balance to the team and started to play better."

Saha went on to score against Rovers for the second time in the tie and Ferguson is delighted with the form of the Frenchman, who has bagged seven goals in his last 10 appearances for the Reds.

"Saha's getting better all the time and the more games he can play the better," added the United boss.

"For twenty minutes of the second half, he was a real problem for Blackburn and he scored another goal which is great.

"I've not asked him if he meant his goal, but as long as the ball ends up in the back of the net, it doesn't matter."