Sources have revealed that Chelsea have made an offer to Porto for midfielder Alvaro Pereira.
Chelsea boss Andre Villas-Boas knows the Uruguay international well after working with him at Porto, before joining the Premier League side this summer.
Following the departure of Yuri Zhirkov, who has joined Russian club FC Anzhi Makhachkala, the Blues are set to sign Pereira, who is likely to be eager to team up with his former boss.
Former Valencia winger Juan Mata is the latest addition to the Chelsea squad following his £26m move, making Chelsea the highest spenders of all the Premier League clubs this summer. Chelsea also recently completed the signing of Romelu Lukaku from Anderlecht.
Pereira joined Porto in 2009 and played a key role in their treble winning season under Andre Villas-Boas last season.
It is understood that Pereira has a £25m release clause, which Chelsea are set to trigger.