Indispensable Pique returns 'home' to Old Trafford with Barca

'I arrived at Manchester United a boy, and I left a man'

All eyes will be on strike duo Lionel Messi and Luis Suarez as Barcelona visit Manchester United in the Champions League this week, but defensive lynchpin Gerard Pique is proving equally important to the Catalans' treble bid.

The centre back returns to Old Trafford for the first time since he left Manchester United in 2008 to rejoin Barcelona, in Wednesday's quarter-final first leg.

Joining the Red Devils in 2004 from Barcelona as a 16-year-old, Pique learned important lessons during some tough seasons in the north of England.

The defender never managed to secure a regular starting spot, with Rio Ferdinand and Nemanja Vidic ahead of him, but was surrounded by elite players to glean wisdom from.

However, after a harrowing afternoon at Bolton Wanderers in 2007 where Pique made a mistake which handed Nicolas Anelka an easy goal, the defender lost the confidence of then-coach Alex Ferguson.

He negotiated a passage back to Barcelona, perhaps the first sign that he would later turn into an entrepreneur as well as an elite footballer.

"I arrived at Manchester United a boy, and I left a man," Pique said in a Player's Tribune article.

"I walked into (Ferguson's) office, and I was honest with him. I said, 'Listen, I feel like I've lost your trust. Barcelona is my home. I want to go back. I hope you will let me go.'"

Pique returned to Barcelona for 5 million euros ($5.62 million) as a reserve with low expectations, but by the end of his first season under Pep Guardiola he had become a key player in the 2008-09 treble-winning side.

There have been ups and downs since, but seven La Liga titles, three Champions League wins and multiple other trophies decorate his honours list, as well as the 2010 World Cup victory with Spain.

Pique has been in sublime form this campaign, driving his side towards another league title, although the trophy the squad wants to win most is the Champions League.

With coach Ernesto Valverde resting the 32-year-old for the first time all season in Spain's top flight, Barcelona shipped four goals in a 4-4 draw with Villarreal last week.

The defender returned to shut out Atletico Madrid in a 2-0 win on Saturday that left Barca 11 points clear with seven matches remaining and attention now turning to Old Trafford.

"I'm coming back to my second home," wrote Pique on Twitter after the Champions League draw in March pitted Barcelona and United together.

Pique denied United in Barcelona's 2-0 Champions League final win in Rome in 2009 and is aiming to pull off the same trick again on Wednesday.

With Suarez and Messi in scintillating form up front, the hosts may need to try and out-score Barcelona, but they will find the man they let go so cheaply standing in their way.