The Premier League club said on Friday that the deal will be completed "subject to a medical and the agreement of personal terms" with the 25-year-old Spain international. (JPN/Agencies)
The transfer will beat the club's record fee of 30.75 million pounds paid to sign Bulgarian forward Dimitar Berbatov from Tottenham in 2008.
Mourinho sad to see Mata on way to United
Jose Mourinho said he was sad to see midfielder Juan Mata leaving Stamford Bridge after confirming that the Spaniard's move to Manchester United was imminent on Friday.
United are expected to complete a club record deal, reported to be 37 million pounds ($61.5 million), for playmaker Mata who has found first-team opportunities hard to come by since Mourinho's return.
"It is a good offer. Respectful to us, respectful to the value of the player. That allows to try to bring another players because we need another player," Mourinho told a news conference. "Sooner rather than later things will be finalised.
"I asked him when the offer comes are you really happy to go and he was saying yes I am really happy to go. After that we could feel mixed emotions.
"We are happy he goes to fantastic situation but we are all sad as well and some of him was a bit the same."
"No one is jumping about because Juan is leaving. We all like him a lot and we can't say you can only go if you go to Russia, to China, to France or Portugal.
"I don't know if Chelsea supporters globally would be happy with that because we are an open club."
Since joining from Valencia for 23.5 million pounds in August 2011 Mata has twice been voted Player of the Year at Stamford Bridge but has slipped below Eden Hazard, Willian and Oscar in the midfield pecking order this season.
"It's a good move for Juan, it's good for the Premier League and the offer was right. We hope Juan does well. We are convinced he will do well. No fears for us."
Mourinho said he was confident the deal to sign Basel's Egyptian playmaker Mohamed Salah would be finalised but said the club would not be buying another striker in the transfer window despite Fernando Torres being injured.
The Premier League club said on Friday that the deal will be completed "subject to a medical and the agreement of personal terms" with the 25-year-old Spain international.