LIVERPOOL manager Rafael Benitez admits he is facing an 'impossible' task at St Andrews tonight.

While the Liverpool manager still has high hopes of ending his second season in charge with a cup final victory by adding the FA Cup to last season's Champions League triumph in Istanbul, he acknowledges that the FA have left him and his players to do it the hard way.

Due to the wishes of Sven-Goran Eriksson - who asked for midweek FA Cup quarter-finals to 'aid' his England team and television schedulers - who have staggered the four ties over four consecutive evenings this week - Liverpool will be forced to play their second away game in three days tonight.

Last night, both Manchester City and West Ham United were also required to play their second game in 48 hours.

Both fell to home defeats in the Premiership on Saturday after each making significant changes to their starting lineups ahead of their clash at the City of Manchester Stadium.

Benitez arguably possesses more strength in depth than either Stuart Pearce or Alan Pardew, but he has been left baffled by having to play two such important matches after just one day of rest.

He said: "It is impossible - you cannot prepare a team to play 100% two days after a fixture.

"That is why we used a different system on Sunday and we will use some different players at Birmingham.

"It is impossible for players to play at the same level in two games in three days."

Benitez explained that this was not just another example of a manager complaining about a busy fixture schedule but a physical fact that footballers need to rest for at least two days after a match.

He said: "After you play a game, you often feel fine on the first day but it is on the second day that things are worse and your muscles are sore.

"On the third day you are maybe back to 70% but you cannot play at the same level. You need time to eat properly, rest and recuperate and this game has come too quickly."