The 30-year-old has since made more than 200 appearances in the famous red shirt, bagging 44 goals in the process.
His first game, however, came in the Premier League immediately after his transfer, against Cardiff City at Old Trafford.
Incidentally, the Spaniard’s opponents on his debut were managed by none other than Ole Gunnar Solskjaer, the playmaker’s current interim boss.
Mata has shared an interesting story from that day, revealing what the Norwegian said to him before he set foot at the Theatre of Dreams for the first time as a Manchester United player.
Mata began he weekly blog with a word of gratitude, as he wrote: “Today I want to start off my post by saying thank you. Honestly, thank you to everyone who has remembered that recently it was five years since I arrived at Manchester United.
“On this exact Monday, as my blog goes up, it is the anniversary of my first game as a Red Devil and it is a date that brings back great memories for me: Old Trafford, the kindness shown by everyone, going from the tunnel onto the pitch, the win…”
“What plenty of you don’t remember is that on that day our current manager was there too… although he was on the opposing bench!” Mata continued, referring to Solskjaer.
“I remember his words in the tunnel before I headed out onto the pitch: ‘Welcome to this fantastic club, Juan, it is incredible, you’ll see. Enjoy it as much as you can and good luck.’ Five years later, we’re both still here.”