United’s reported £37 million (44.5 million euros) move for Mata will be completed subject to the 25-year-old passing a medical and negotiating personal terms with the Premier League champions.
The transfer would shatter United’s previous record fee of £30.75 million paid to sign Bulgarian forward Dimitar Berbatov from Tottenham in 2008.
“Manchester United is pleased to announce it has reached agreement with Chelsea Football Club for the transfer of Juan Mata for a club-record fee,” United said in a statement.
“The deal is subject to a medical and the agreement of personal terms. A further announcement will be made in due course.”
Mata is expected to have his medical on Saturday and, unless there are any hitches, he should make his United debut in Tuesday’s Premier League clash against Cardiff at Old Trafford.
United manager David Moyes desperately needed a high-profile signing to lift the gloom after a miserable start to his reign as Alex Ferguson’s successor.
Since replacing Ferguson in July, Moyes has seen United fall 14 points behind Premier League leaders Arsenal, while they also crashed out of the FA Cup in the third round against Swansea and suffered an embarrassing League Cup semi-final loss to Sunderland in midweek.
Moyes had been keen to land a quality midfielder since arriving from Everton and he made failed bids for several top stars, including Barcelona’s Cesc Fabregas, before the last transfer window shut in September.
His swoop for Mata should add much-needed creativity and intelligence to United’s midfield, although the champions also need a more aggressive ball-winner in the mold of former Old Trafford great Roy Keane.
Mata, who cost Chelsea £23.5 million from Valencia in 2011, became available after falling out of favour with Chelsea manager Jose Mourinho.
He won Chelsea’s player of the year award for the last two season and has 32 caps for Spain, but failed to impress Mourinho.
He was repeatedly left on the bench and even when he cracked Mourinho’s line-up he was replaced in nine of his 13 Premier League starts this season.
Mourinho has given Eden Hazard, Oscar and Willian the main attacking roles and the Portuguese coach conceded Chelsea’s system does not suit Mata, who reportedly asked to leave after being substituted during a match at Southampton earlier this month.
It had seemed the deal might be delayed while Chelsea tied up their move for Basel’s Egypt winger Mohamed Salah, but Mata has been given the green light to quit Stamford Bridge.
“It’s what he wants,” Mourinho earlier on Friday before United confirmed the deal.
“It’s what he asked us to accept. Chelsea Football Club is proud to act this way, in an open way, in a human way.
“The offer, compared with what the club paid two years ago (when Mata signed from Valencia), was fantastic.
“If Manchester United pay their record for a player it’s because they know exactly what they want. They are convinced he’s going to be important for them.”
Keen to preserve his place in Spain’s World Cup squad, Mata has jumped at the opportunity to help revive United’s fortunes.
His signing also underlines the determination of United’s owners, the Glazer family, to back Moyes after growing criticism of the Scot’s torrid start at Old Trafford.
Former United captain Bryan Robson believes Mata’s arrival is a step in the right direction.
“It’s what everybody has been talking about for a couple of seasons now,” Robson told Sky Sports News.
“Michael Carrick has been very consistent but everybody else has struggled to stamp their authority in there.
“I still feel it’s an area we need to strengthen but it’s only David Moyes and his staff who can make those decisions.
“But new signings, especially when they’re top class, can give an injection of enthusiasm within the squad.”