The Spanish coach took over at the Catalans in the summer of 2008 following the departure of Frank Rijkaard to lead them to six domestic, European and international triumphs during glorious one-and-a-half years.

After winning the treble least season, Barcelona clinched the Club World Cup title with a 2-1 comeback victory over Argentina's Estudiantes after extra time on Saturday.

"Winning six titles in a row was unthinkable. I didn't think I'd be strong enough to do that," Guardiola was quoted as saying on the club's official website.

"There have been a lot of factors involved: very few injuries, a group of players that play because they enjoy it, mental strength…

"We all have the right to feel happy, and I congratulate all the people who love Barca. This was for them."

Barcelona trailed to Mauro Boselli's first-half goal but substitute Pedro notched the equalizer with one minute remaining to force an extra time.

Ballon d'Or winner Lionel Messi, who is also favorite to win the FIFA Player of the Year award, chested the winner in the 110th minute.

"Today I want to thank the players for all the months they have given us," Guardiola added.

"They have played very well at times, doing what people enjoy. I will never forget that it was them who have made me great."