Manchester United introduces three new signings: Morgan Schneiderlin (L-R), Bastian Schweinsteiger, and Matteo Darmian, at a news conference in Bellevue, Washington July 15, 2015. [Photo/Agencies]

The 30-year-old Schweinsteiger scored 45 goals and set up 70 more in 342 league games for Bayern. He joined the club's youth sides from Rosenheim in 1998 and went on to win the Bundesliga a joint-record eight times, matching former club stalwarts Mehmet Scholl and Oliver Kahn.

"It's a good challenge for me," Schweinsteiger said of moving to the Premier League. "I want to give my impact here and make (it) a positive one."

His signing was the highlight of an offseason where United focused on bolstering its midfield. Schneiderlin was brought in after spending seven years at Southampton and watching the club grow from lower division to being a steady Premier League participant.

Schneiderlin was linked to a number of clubs, but he never questioned where he was headed.

"When I learned Manchester United was interested there was no other choice," Schneiderlin said.

Darmian came from Torino in Italy and van Gaal sees him as an upgrade as an outside defender with the ability to push forward into the attack when needed.

There are still questions about United's attack with the Premier League opener against Tottenham less than a month away, especially after the departure of van Persie, who moved to Fenerbache. Van Gaal said he was clear with van Persie at the end of last season that he would be moving on from United and was happy with his decision to join the Turkish club.

"I had already communicated at the end of the season and he knew already what was coming," van Gaal said. "I think he made a very good choice."