Chelsea have agreed a fee with Spanish club Valencia to sign Juan Mata for a reported £23.5m.
The Stamford Bridge club said the deal was subject to the winger, 23, agreeing personal terms and passing a medical.
No fee has been officially disclosed but reports in Spain suggest the Blues are paying £23.5m.
"An agreement has been reached with Valencia CF for the transfer of midfielder Juan Manuel Mata," a statement on the Chelsea website said.
"The move is now subject to the player passing a medical and agreeing personal terms."
Valencia had confirmed the deal themselves earlier on Sunday.
After Chelsea's 2-1 win over West Brom, boss Andre Villas-Boas said: "He can add to any squad in the world."
Mata has been at Valencia since 2007 and as captain helped Spain win the Under-21 European Championship in the summer. He was also part of Spain's 2010 World Cup winning squad.
Villas-Boas has previously spoken of the need to recruit more midfielders and the club have also made bids for Tottenham's Luka Modric.
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Andy Brassell,
European football expert
You can argue Mata brings something Chelsea have lacked since Arjen Robben left - a player with real acceleration who can put defenders on the back foot. I do not think it means an end to Chelsea's efforts to sign Luka Modric as, while Mata can play in the centre, I would be very surprised if he did for Chelsea. I would imagine he will play on the right with Florent Malouda on the left. He is creative and has two good feet, although he is predominantly left-footed. Mata is quite a modest and down-to-earth guy and can be a key player for Chelsea for years to come.
On Saturday after Chelsea's 2-1 win against West Brom Villa-Boas was questioned about Mata.
He refused to be drawn on whether any deal was close, but he said: "He's a good player, a very good player.
"He's not our player but he's an interesting player.
"His curriculum speaks for itself. He's a player who scores and assists and he can add to any squad in the world."
Mata joined Valencia from Real Madrid's youth team. Last season, the 23-year-old midfielder, who is 5ft 7in tall, scored eight goals to help Valencia to a third-place finish in the Primera Liga.
He was also part of Spain's 2010 World Cup-winning squad and captain of the under-21 team that won the European Championship this year.
If Mata leaves, Valencia will have sold all four of their World Cup winners, with Mata following David Villa (Barcelona), David Silva (Manchester City) and Raul Albiol (Real Madrid) out of the club.
