Andre Villas-Boas is known to be keen to add to his midfield, both to increase numbers and to inject creativity after the team struggled to provide record signing Fernando Torres with sufficient service after his move from Liverpool in January.
Luka Modric is still said to be on the club's radar - though Villas-Boas told a press conference on Thursday that the continuation of the pursuit will be the "club's decision" - but widespread reports in England and Spain suggest that, for now, attention has turned to 23-year-old Mata.
Marca reported the news of Chelsea's interest earlier this week, and Valencia-based SuperDeporte claims "talks between the directors at the London club and Valencia have intensified". The Las Provincias newspaper says Chelsea are ready to pay between €25 million and €30 million, and that Valencia would accept, with Sergio Canales' arrival from Real Madrid offering adequate cover.
The Daily Telegraph, more specifically, claims Chelsea have bid £27 million and adds: "The offer is expected to secure the 23 year-old from Valencia, who are likely to accept the bid ahead of interest from Tottenham Hotspur." The Daily Mail, which reported that Chelsea had seen a £22 million bid for Mata rejected earlier this week, also puts the value of the bid at £27 million but claims the offer includes a further £2 million in top-up payments.
Asked to comment on links with Mata, Raul Meireles and Porto duo Joao Moutinho and Alvaro Pereira, Villas-Boas would only say: "We have been studying all kinds of options."
With their young manager at the helm, Chelsea have been eager to inject youth into the playing staff, and on Thursday completed the signing of 18-year-old Belgium striker Romelu Lukaku. Villas-Boas has tipped the youngster for great success at Stamford Bridge.
"He is tremendously powerful, very strong in the challenges," he said. "Despite his size, he has an explosiveness and an ability to react quickly which looks pretty amazing. He just has to break through this competitive level and, for sure, he will get opportunities this year."