The veteran playmaker was initially reluctant to leave the club, having been named Player of the Year in his first two campaigns in west London, but later opted to accept a move to United.
Mata said in the latest episode of the UTD Podcast: "When Manchester United called and they said "We're going to go for you and make an offer to Chelsea, we want you to come", I spoke with them. I really wanted to go and really wanted to feel what it is to be a Manchester United player.
"I had suffered playing against United with Chelsea and they are definitely one of the biggest clubs in the world. At that moment, they were struggling with the first season of [David] Moyes and were not doing great in the league, but that doesn't matter. I wanted to come to be a player for this club.
"I spoke to Chelsea and said: 'Listen, there is this offer. It's also good money and you can sign another player, because I'm telling you so that you have time to sign another player. I'm not playing a lot and want to take this opportunity. It's perfect for everyone'. So it happened."