Jose Mourinho says selling Juan Mata is the right thing to do, because the player himself wants to move on.
He also says it would have been wrong to resist dealing with Man United simply because they refused to play ball over Wayne Rooney.
The Chelsea boss insists the Spanish midfielder would still have had a big role to play at Stamford Bridge, had he not opted to leave, and is sorry to see him go.
“I asked him when the offer came: 'Are you really happy to go?' and he was saying yes, so after that we could feel mixed emotions,” Mourinho said.
“We are all happy he goes to a fantastic situation, but at the same time we are all sad. It's good for Juan, good for the Premier League and, in financial terms, is a good offer for us.
“He was fantastic for Chelsea and Chelsea was fantastic for him. We are not afraid of him doing well there. We want him to be happy and to do well.
“I still think he could be important for us, even though he has not been playing a lot. But Juan had this fantastic opportunity at a big club in a country where he loves to play.
“It's the right offer for us so in spite of the fact many clubs, boards and managers think not to sell to a rival club, we think differently.
“Chelsea is proud to do it this way. If we say you cant go because United wouldn't sell us Wayne Rooney, I don't think that's fair to Juan.
Mourinho added: “He was clearly disappointed and frustrated here [not to be playing every week] and if he cannot be fully happy and has another big club who wants him, you cannot stop people.
“The player deserves respect and to play where he wants to play, so we allow him to negotiate with them and not close the door.
“It's a good offer, respectful to us and to the value of the player that allows us to bring in another player and still have a fantastic profit.
“With this deal, and one for Kevin De Bruyne, we also put ourselves in a fantastic position with financial fair play.”