After leading Barca to a record 13 trophies in four seasons, Guardiola said on Friday he was quitting because he felt drained and president Sandro Rosell announced Vilanova would take charge of the first team from next season.
Guardiola has often spoken of his reliance on his close friend - who was a contemporary at the club's youth academy - and it is Vilanova to whom he turns for advice when strategic changes need to be made during games.
The two have similar personalities. They are softly-spoken, hard-working and methodical students of the game who are devoted to the unique brand of fast-flowing, possession-based football they had drummed into them at the academy.
While Vilanova, 42, may not command the instant respect Guardiola's successful playing career afforded him, he has a close relationship with the Barca squad, particularly the home-grown members, many of whom he coached when they were teenagers.
After his own mediocre playing career at clubs including Celta Vigo and Elche ended, he returned midway during the 2001/02 season to take charge of a youth team featuring Lionel Messi, Cesc Fabregas and Gerard Pique.
"For Tito, I wish the best in this new opportunity that football has given to him," Fabregas wrote on his Twitter feed on Friday.
"We were together when I was a kid and he is not just a great person but also an excellent manager," added the former Arsenal captain, who shares his full first name of Francesc with Vilanova.
Vilanova was at Guardiola's side when they led the B side to promotion to the Spanish third tier in 2007 and has been a constant presence in the four seasons they have run the first team apart from a brief period of convalescence late last year following surgery on a tumour in his saliva glands.
Guardiola has always expressed his gratitude to former president Joan Laporta for taking a punt in 2008 and handing him his first top-flight coaching role with only a year's previous experience in a Spanish regional league.
At his farewell news conference on Friday, the 41-year-old said the board of directors had made a wise decision.
"He is a capable person whom the players already know," Guardiola said.
"I was just the spokesman for ideas we developed together and he will give this club and these players what I no longer can give them."
Vilanova will have some adjustments to make to the squad, with players like club captains Carles Puyol and Xavi in the twilight of their careers and full-back Eric Abidal recovering from a liver transplant.
Like Guardiola before him, he will have a rich pool of talent to choose from in the club's youth ranks and bringing young players through is a trait of his former boss that is likely to be repeated.
For now, Barca have four La Liga games left with both Guardiola and Vilanova on the bench, as well as a King's Cup final against Athletic Bilbao next month.
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