Brazil international Alisson has joined Liverpool from Roma in an $84 million transfer -- a world record deal for a goalkeeper.
"In terms of my life and my career, it's a huge step for me being part of this club and this family," the 25-year-old Alisson told the Liverpool website after signing a reported six-year contract. "You can be certain that I'll give my all."
Brazilian has been with Roma for two years
Previous record for goalkeeper was ($61m) for Gianluigi Buffon
Serie A club Roma said Alisson would join for an initial fee of $72.7 million, but the transfer's performance-related clauses could see the fee rise to $84 million.
Earlier Roma's sport director Monchi said that Liverpool's "offer was way above the market average -- it was very significant."
The transfer makes the Brazilian the most expensive goalkeeper in history, his fee eclipsing the $62 million Juventus paid to Parma in 2001 for Gianluigi Buffon and the $46 million Ederson cost Manchester City from Benfica last summer.
"There was a world-class goalkeeper on the market, and the club gave us the opportunity to sign him -- simple as that," said Liverpool manager J-rgen Klopp.
"He's a very calm person," added Klopp. "It's not his price, it's not the price we want to pay, it's only the price the market demands. That's how it is, no problem with that.
"The size of the story is only outside [the club]. We don't think about that. We know what everyone will say about this, but it's not really important. We have now another wonderful player in our squad and that's the only thing we are looking for."
Monchi defends sale
Just over a year ago Liverpool signed Mo Salah from Roma for $49 million and given the Egyptian international performances for the English Premier League side -- he scored 32 league goals in 38 games and helped them reach the Champions League final -- Monchi's transfer strategy has come under scrutiny.
"The job of a sporting director is not just to make signings but also to understand what's best for the club at any given time," said Monchi as he reflected on Alisson's transfer.
"Economic factors are important for the club too, not just sporting factors.
"We weighed up the pros and cons and decided to speak to Liverpool in order to come to an agreement. Does it show a lack of ambition? Not for me."
Alisson, who played in all five of Brazil's World Cup games in the summer, is the English Premier League side's fourth signing of the summer, following Naby Keita, Fabinho and Xherdan Shaquiri.
He will replace Loris Karius as the club's No.1 goalkeeper with the German having failed to impress between the sticks last season, a campaign which culminated in a calamitous performance in the Champions League final where his errors led to two Real Madrid goals in a 3-1 June defeat in Ukraine.
Goalkeeper has a problematic position for Liverpool in recent years -- neither Karius nor Simon Mignolet have made a big impact -- and the club will hope that the signing of Alisson will help its quest to improve on last season's fourth-place finish.