A crowd of over 70,0000 will pack into the Pasadena Rose Bowl to watch Van Gaal's United take on the Los Angeles Galaxy.
The match may be taking place over 5,0000 miles away from Manchester, and it may start at 3,30am, but United fans will closely watch every move Van Gaal makes.
Several hints about how Van Gaal's plan for United will be gleaned from the friendly, which is the opening encounter in a two-and-a-half-week long tour that takes in Denver, Washington DC and Detroit.
The Dutchman has been using a 4-3-3 formation in training this week and it will be interesting to see if he adopts the same tactics against the Galaxy.
Whatever system he selects, the players on show will be keen to impress their new manager.
This tour is effectively an audition for the players. If they needed a reminder they are playing for their futures, then Ed Woodward delivered it in an MUTV interview at the weekend when he said there would be incomings and outgoings over the next few weeks.
Great things were expected of Zaha when he arrived at United last summer following his B£15million move from Crystal Palace, but he soon fell out of favour with David Moyes and he was loaned to Cardiff for the second half the season.
The England international is one of many players hoping to make an impression on Van Gaal.
"It's great to be back," Zaha told manutd.com.
"There's a nice vibe, everybody's working hard and we're looking forward to the new season.
"For me, I definitely feel like this is a clean slate.
"All I'm trying to do is impress the new manager and get into his squad. All I can do is give my all. There's a new manager and I want to make sure I show him what I can do."
When Moyes named Zaha in his Community Shield team last August, many expected the winger to hold down a first-team place for the rest of the season.
The 21-year-old did not start a league match for United though after Moyes decided the player was not good enough.
After a 13-game loan spell in Wales, Zaha feels he has improved.
"Going to Cardiff was a really good experience for me," he said.
"I managed to get quite a few games under my belt at Premier League level, which was good, and I feel like I've come back a better player.
"I've realised there are things about my game I need to work on and concentrate on and I know this is the best place to be if I want to improve. I really want to make myself a better player."
There will be a familiar face in the opposition starting XI at the 92,000-capacity Rose Bowl.
Robbie Keane, now in his third year at the Galaxy, used to play against United on a regular basis for Tottenham and Liverpool.
Keane spent a month on loan at Aston Villa two years ago, but he opted against returning to the Premier League last season despite interest from several clubs.
The Republic of Ireland captain is happy in California and does not miss the Barclays Premier League.
"I don't hanker for England, not at all," the striker said.
"I speak to a lot of players in England, but my routine has completely changed.
"My summer is playing now and I have Christmas off.
"That is quite nice. I spent my first time in Ireland for 17 years at Christmas.
"I look forward to it again this Christmas. It has completely changed for me.
"Going back is not something I have looked into too much."
- Sports & Recreation
- Van Gaal
- Los Angeles Galaxy
- Wilfried Zaha