By Iain Rogers
BARCELONA (Reuters) - Andres Iniesta admitted this week that Barcelona suffer from "Messi-dependence" and his view was painfully highlighted as the favourites laboured in the Champions League quarter-final clash against Paris St Germain on Wednesday.
Messi started on the bench at the Nou Camp after straining a hamstring in last week's 2-2 first leg draw in Paris and for the hour before his introduction, Barca produced a flat performance despite the best efforts of the home fans to rouse the players.
Cesc Fabregas was deployed in Messi's roving forward role as he had been on Saturday when he scored a hat-trick against Real Mallorca in La Liga, but the Spaniard made little impact as passes went astray and possession was surrendered all to easily.
A fired-up PSG side stuffed with expensive talent were an entirely different proposition to Mallorca and the Ligue 1 leaders came close to inflicting a first home defeat on Barca in the Champions League in 21 games since October 2009.
When Messi replaced Fabregas in the 62nd minute, Barca were losing 1-0 on the night and 3-2 on aggregate thanks to Javier Pastore's breakaway goal five minutes after halftime.
The mere sight of Messi warming up had already lifted the palpably nervous fans and when the Argentina international entered the fray, Barca were transformed.
He was clearly short on fitness but it was his clever pass to David Villa with around 20 minutes left that allowed the Spain forward to feed his international team mate Pedro, who cracked a first-time shot past Salvatore Sirigu.
With Messi on the pitch, a reliable link between the forward and the midfield was restored, and Barca were better able to control possession and see out the game to secure a sixth straight appearance in the last four.
"In Leo we are talking about the best player in the world and when things are not going well you have to use him," centre back Gerard Pique, who came through Barca's youth ranks with Messi, told reporters.
"Even if he is half lame, his presence on the pitch is enough to lift us and our play in general," added the Spain international, one of nine in the starting lineup against PSG.
While Barca's subdued performance without their talisman was a concern, they can comfort themselves with the knowledge that he is likely to be fully fit for the semi-final, first leg in two weeks time.
"At this point he doesn't have any physical problems," assistant coach Jordi Roura told a news conference.
Arch rivals Real Madrid, last year's runners-up Bayern Munich and the side they displaced as German champions at the weekend, Borussia Dortmund, are also through and the draw for the last four will be made on Friday.
"It feels like it's a duel between the Spanish and German leagues and I really have no preference," Barca sporting director Andoni Zubizarreta told reporters.
"For better or for worse, we showed that like a Manchester United or a Bayern Munich, we can make it through whether we are playing poorly or playing well," added the former Barca and Spain goalkeeper.
With Messi, who has 59 Champions League goals in 77 appearances, second behind only former Real striker Raul, back to full fitness Barca have every chance of securing a third European crown in five years and their fifth overall.
(Editing by John O'Brien)