Chelsea are poised to complete the transfer of Valencia winger Juan Mata in the next 48 hours after the two sides reached "an agreement in principle" for the 23-year-old.
Neither club has revealed the fee involved but reports in the Spanish press suggest Mata will cost Chelsea £26m, subject to the winger passing a medical on Monday.
"An agreement has been reached with Valencia CF for the transfer to Chelsea of midfielder Juan Manuel Mata," Chelsea's statement read:
"The move is now subject to the player passing a medical and agreeing personal terms."
Mata joined Valencia from Real Madrid in 2007 and was a key member of Spain's Under-21 success at this summer's European Championship in Denmark. His arrival follows the signings of Romelu Lukaku and the midfielder Oriol Romeu at Stamford Bridge this summer.
The signing of Mata is likely to precede the arrival of Luka Modric, after the Croatian midfielder was left out of Tottenham's squad to face Manchester United on Monday night.
Chelsea have been pursuing Modric, 24, all summer and have already had two bids of £22m and £27m rejected by Tottenham chairman Daniel Levy.
Nevertheless, Roman Abramovich is prepared to make a new £30m offer for the Croatian playmaker, after Tottenham manager Harry Redknapp admitted the midfielder "is not in the right place" to play in Monday's game.
Spurs have steadfastly refused to countenance any offers for Modric, but may now struggle to keep the player after he effectively went on strike to force through a move across London.
"He's got a little bit of an injury," Redknapp told TalkSport. "There's a possibility he could have played through it. But at the moment his head's not in the right place."
Modric didn't feature in last Thursday's Europa League play-off first leg against Hearts because of injury and on Sunday Redknapp told the Telegraph:
"It's been difficult for us. He's not here against United. He's got a little bit of an injury but probably not that bad and there was the possibility that he could have played through it, but at the moment his head is not in the right place. So it's been a problem for us. We need him playing, he's very important to us."
Meanwhile, Chelsea striker Daniel Sturridge has been linked with a move to Liverpool as Villas-Boas steps up his interest in midfielder Raul Meireles.
The Portuguese is keen to bolster his creative options in midfield and is willing to offer Sturridge as part of a deal bringing Meireles to west London, according to unconfirmed reports.