It is tempting to assume that Van Gaal will use a similar system—and similar personnel—to the side which destroyed the Galaxy on Thursday morning.
However, given the impressive performances of the second-half understudies in that game, will Van Gaal add some of those names to his starting XI?
There is sound logic in Van Gaal continuing to play what he perceives to be his strongest side. Given the confidence-destroying season that United had last time out, a pre-season which sees them recast as contenders could provide a huge psychological boost.
Van Gaal used David de Gea in goal in the first half and Anders Lindegaard in the second against LA. With Ben Amos and Sam Johnstone also in the touring party, it will be intriguing to see if either of them get a chance. De Gea is probably favourite to start, based on the assumption that Van Gaal wants to continue to put out his strongest side.
Assuming the new boss is set on making 3-4-1-2 United's default formation, there is an immediate selection dilemma in the wing-back roles.
Luke Shaw has been brought in at great expense to be United's next left-back, or indeed left wing-back. Given Reece James' second-half brace, however, Shaw may face competition for a place in the starting XI here.
On the right flank there is a different kind of decision to be made. There is a straight fight between Rafael da Silva and Antonio Valencia for the right wing-back berth. Da Silva offers better defensive nous, Valencia more raw power and acceleration going forward.
Perhaps Van Gaal will be swayed by the higher calibre of the opposition and play the defender in the role.
Phil Jones, Chris Smalling and Jonny Evans look to be the back three for Van Gaal. Presumably he will welcome the chance to give them further minutes in their new role together.
In the centre of the park, Ander Herrera and Darren Fletcher were the only two United players to play 90 minutes against the Galaxy. Both were asked to change their role at half time, with Herrera moving up the pitch and Fletcher dropping into defence.
Herrera was absolutely outstanding against LA and it would be a surprise to see him left out on Saturday. Fletcher had a fine game too, but perhaps Van Gaal will be tempted to see whether Herrera and Cleverley can work together in the deeper-lying midfield positions.
Juan Mata was another player whose performance caught the eye on Thursday and it would be a delight to see him reprise his free role behind the forwards against Roma.
Danny Welbeck opened the scoring for United against the Galaxy and he provided some excellent link-up play. His willing running is partly what allowed Mata to roam so freely. Welbeck also offers an aerial presence which allows United's defenders to bypass midfield and hit long balls forward when necessary.
If Van Gaal is looking to make Wayne Rooney a central part of the United team, it seems likely he will play against Roma.
According to all this speculation, the United side might look something like this.
Of course, it is far too early to know what Van Gaal will do. It would not be a shock to see a completely different line-up, especially one featuring more youngsters from the off.
It will be interesting to see if Van Gaal once again plays a different side in each half and, if he does, which of the players on the periphery get a run out this time around.
As a United fan, it is hard not to be a little giddy about the prospects on offer under Van Gaal's leadership. If United impress again against Roma, that giddiness will only grow.