By Iain Rogers
MADRID, March 11 (Reuters) - Sergio Aguero has a proven scoring record against Barcelona and the Manchester City forward may have a crucial role to play if his side are to upset the odds and reach the Champions League quarter-finals for the first time.
City trail 2-0 ahead of Wednesday's last 16, second leg at the Nou Camp, a Lionel Messi penalty and a late Daniel Alves goal in Manchester last month putting the Spanish champions on the brink of their seventh consecutive appearance in the last eight of Europe's elite club competition.
Aguero, who missed the first leg through injury but returned for City's English Capital One (League) Cup final victory on March 2, scored five goals in 10 La Liga games against Barca for Atletico Madrid between 2006 and 2011.
They included a dramatic winner, his second of the match, in a 4-3 success at the Calderon in the 2008-09 season that prompted the kind of wild celebrations he unleashed with the goal that sealed the Premier League title for City in 2012.
The player, known as "Kun" after a Japanese cartoon character, also netted a double in the same La Liga fixture a year earlier, a 4-2 win for Atletico.
He has never tasted victory at the Nou Camp though in six visits but did score in a 1-1 draw in 2006-07.
"As always in important games the individual performance of players is key," City coach Manuel Pellegrini, who has labelled Aguero the third best player in the world behind his Argentina team mate Messi and Portugal forward Cristiano Ronaldo, said on the club's website (www.mcfc.co.uk) on Monday.
"Of course it's difficult," added the Chilean, in his first season in charge following stints in Spain with Villarreal, Real Madrid and Malaga.
"But I don't have any doubt that we are going to Barcelona thinking that we can do it, that we can beat them in Camp Nou and we will try to have our revenge there."
Pellegrini also has experience of Barca's daunting arena, Europe's biggest stadium. He faced them 22 times during his La Liga coaching career but only managed four victories, most recently a 2-1 win for Villarreal at the Nou Camp in March 2008.
He lost both "Clasicos" against Barca as Real coach in the 2009-10 season, 1-0 away and 2-0 at home.
"It's difficult because they are a very good team with great players and that's the most important thing," Pellegrini said.
"We will try to get the tempo we need to score goals. If we can score a goal early Barcelona may be more nervous.
"There are so many things affecting the outcome of big games that it is very difficult to know what will be the key factor. If we have a good day I am absolutely sure we can do it."
Pellegrini's players will take heart from a fine performance in Germany in their last European away game when they came from two goals down to beat Group D rivals and defending champions Bayern Munich 3-2 with both teams already through to the last 16.
History is against them, however.
Only twice in Champions League history has a team recovered from a first-leg defeat at home to go through, Ajax Amsterdam achieving the feat in 1995-96 and Inter Milan following suit in 2010-11.
Both City and Barca are coming into the match after surprise defeats, Barca going down at lowly Real Valladolid and slipping to third in La Liga and City losing to second tier Wigan Athletic in the FA Cup quarter-finals.
"It was a strange game (at Valladolid), but we have to put it behind us now and not feel sorry for ourselves," Barca's Chile forward Alexis Sanchez said on Monday.
"We have to be positive because we have an important game ahead," he told a news conference.
"I am hungry to win and so are all my team mates. We want to win everything, La Liga, the Champions League and the King's Cup. I don't know anyone in the squad who doesn't want that." (Editing by Mark Meadows)