Manchester United have had a club-transfer-record £37 million bid for Chelsea midfielder Juan Mata accepted, according to the BBC. Mata is due for a medical on Thursday before completing his move to the Premier League champions, and is expected to sign a four-and-a-half year contract. The Spain star, who made 135 appearances for Chelsea over the course of two-and-a-half seasons at Stamford Bridge, said goodbye to his teammates at the Blue's Cobham training ground on Wednesday. United continue to deny making the bid, but it is understood they have made an offer through intermediaries working on the deal. Should the deal go through, Mata's arrival would put in the shade the £30.75 million the Red Devils paid Spurs for Dimitar Berbatov in September 2008, their previous club-record bid. Mata has been linked with a move away from Chelsea for much of the January transfer window after struggling to hold down a place under manager Jose Mourinho. The former Valencia star has not played for the west London club since New Year's Day, with his last appearance coming against Southampton. Despite this, he was twice named Chelsea's Player of the Year for 201112 and 201213, and scored 20 goals and provided 35 assists last season. Chelsea paid £23.5 million to sign Mata from Valencia in 2011.