MADRID, April 22 (Reuters) - A fading Barcelona will need to recapture the sort of form that made them the kings of Europe two years ago if they are to tame much-fancied Manchester United in their Champions League semi-final on Wednesday.
Once seen as the leading exponents of the beautiful game in club football, Barcelona are a mere shadow of the side that took the competition by storm in 2006 and it is now United who are deemed the most attractive and exciting team on the continent.
Barca effectively waved goodbye to their chances of depriving Real Madrid of the league title after labouring to a 0-0 draw at home to neighbours Espanyol on Saturday.
They have won only one of their last eight league games and they were distinctly unimpressive during their 1-0 victories over Schalke 04 in the last round of the Champions League.
Barca's hopes rest in great part on Lionel Messi, who is back fit after missing the last round because of a thigh injury.
The 20-year-old Argentine missed the 2006 Champions League final through injury.
Barca will be without their former talisman Ronaldinho who is sidelined with a leg injury and looks to be on the way out of the club after a worrying slide in form this season.
Thierry Henry is a doubtful after missing the Espanyol because of flu and coach Frank Rijkaard is likely to opt for youngster Bojan Krkic alongside Messi and Samuel Eto'o up front.
Barca will also be missing skipper Carles Puyol who is out through suspension, meaning that Rafael Marquez and Gabriel Milito are likely to pair up in the centre of defence. Eto'o, who has threatened to leave the club if they do not get back to winning ways, has said that United's status as favourites will serve as an extra incentive.
"For me it is a big motivation that they are being classed as the favourites, that makes me even more keen to beat them," he said.
For United the match at the Nou Camp will mark a return to the venue of their famous 2-1 win over Bayern Munich in the 1999 Champions League final.
That victory came when Teddy Sheringham and Ole Gunnar Solskjaer scored in stoppage time to secure their treble success of Premier League, FA Cup and Champions League honours.
Another victory there on Wednesday would take them one step nearer a double this season of Premier and Champions League honours.
However, Alex Ferguson does have some injury concerns, mainly regarding Owen Hargreaves and Anderson. Hargreaves has a hamstring injury and missed Saturday's 1-1 draw at Blackburn Rovers, as did Anderson who has a groin problem.
Goalkeeper Edwin van der Sar (groin) was rested for the Blackburn game, while striker Wayne Rooney injured a hip at Ewood Park but should be fit enough to play on Wednesday.
The match could be a significant for United's Paul Scholes and Gary Neville, who would make their 100th Champions League appearances if they play.
Scholes, Neville and Ryan Giggs are the only survivors from the treble-winning squad of 1999, although the Scholes was suspended for the final against Bayern.
Barcelona: 1-Victor Valdes; 11-Gianluca Zambrotta, 4-Rafael Marquez, 3-Gabriel Milito, 22-Eric Abidal; 6-Xavi, 24-Yaya Toure, 8-Andres Iniesta; 27-Bojan Krkic, 9-Samuel Eto'o, 19-Lionel Messi.
Manchester United: 1-Edwin van der Sar; 6-Wes Brown, 5-Rio Ferdinand, 15-Nemanja Vidic, 3-Patrice Evra; 16-Michael Carrick, 18-Paul Scholes, 7-Cristiano Ronaldo, 32-Carlos Tevez; 11-Ryan Giggs, 10-Wayne Rooney.
Referee: Massimo Busacca (Switzerland) (Additional reporting by Mike Collett in London)