The Spain playmaker lined up alongside Wayne Rooney and Danny Welbeck in a three-pronged attack but how did he fare against the Champions League winners that included the likes of Gareth Bale, Isco, Sergio Ramos and Luka Modric their starting XI.
Goal takes a look at how the 26-year-old got on in Michigan, while also pondering what the future may hold for the former Chelsea midfielder...
|PERFORMANCE AGAINST REAL MADRID
Starting in a fluid attacking triumvirate alongside Danny Welbeck and Wayne Rooney, Mata was given the freedom to go and express himself against Carlo Ancelotti's side and he didn't disappoint as United claimed an impressive 3-1 win.
The Spain international looks invigorated and eager to impress after a disappointing World Cup that saw him play just 34 minutes in Brazil and he looked dangerous every time he received the ball in and around the Madrid box.
His runs from deep in behind the Madrid defence were causing problems for the likes of Pepe and he appeared to thrive in Van Gaal's fluid 3-4-3 system that gave him plenty of room to pop up in numerous positions across the front line.
With Ander Herrera and Darren Fletcher happy to do more defensive work behind him, Mata was able to pull the strings further forward and he was unlucky not to find the back of the net during a productive opening half, picking up on Rooney's clever free-kick only to volley an attempt wide.
The 26-year-old was eventually replaced in the second half for Shinji Kagawa but Van Gaal will be encouraged by the playmaker's performances despite him not being directly involved in any of United's three goals.
|WHAT DOES THE FUTURE HOLD?|
Despite United's struggles under David Moyes, Mata was one of his side's plus points in the second half of the 2013-14 campaign and the former Chelsea man will want to continue to prove his value to the club after they splashed out a record fee back in January.
Cementing his place in Van Gaal's starting XI will be a priority and he will be desperate to become a mainstay in the Dutchman's new-look United side, where there is plenty of competition for an attacking midfield berth.
At 26, Mata is reaching his peak years and if he wants to be known as one of the very best attacking midfielders in world football, he needs to deliver at at time when United will need him most in their quest to be competing for the top titles once again.
After being overlooked by Vicente del Bosque for much of the World Cup, Mata will also be keen to stamp his mark on the Spain team in the coming months and a fast start to the Premier League campaign in a United shirt will do his international chances no harm at all.
|A GOOD SEASON WOULD BE...|
Mata will be determined to help Van Gaal's side get back to their dominant best and ensuring at least a top-four finish is the bag come next May will undoubtedly be at the top of the agenda for club and player.
Van Gaal is a hard taskmaster, though, so hitting the ground running will be important for all of United's big-name stars, regardless of reputation or price tag and Mata will need to impress in the early weeks of the season to ensure he is a United regular.
A failure to immediately bounce back into at least the Champions League spots would be disastrous for United and their new manager but with talented players such as Mata at the new manager's disposal, one would not bet against them being a force in the Premier League next season.