If his attitude and form don't improve dramatically before Christmas, some hard decisions will have to be made. Van Gaal has a history of not respecting reputations, and he may well go back on his promise to play Rooney if he deems it necessary.
When Burnley first entered the Premier League back in 2009 they may have been relegated finishing 18th, but at least Turf Moor became somewhat intimidating as they won their first four fixtures at home. So far two draws and a defeat hasn't set them up anywhere near as well as for that season, and they went back down then!
Losing your best player will always have an adverse effect on a team. Liverpool have struggled this season following the sale of Luis Suarez to Barcelona, while Tottenham failed to sufficiently replace Gareth Bale after his record breaking move to Real Madrid. Athletic Club are following suit having floundered through the first 6 weeks of the campaign on the back of Ander Herrera's big money move to Manchester United.
It is utterly bemusing that the team still possesses such imbalance that they will - until serious changes are made - still be fully capable of being out-scored. By the time January comes around and yet more millions are dished out on the one area of the team most glaringly in need of strengthening, it could be too late.
While transfer negotiations were sill going on, the team were struggling on the pitch. But now that the window has closed and the squad is complete, United look an altogether different beast.
Injuries are, unfortunately, a part of the beautiful game, and can influence a team's season far more than fans would like. Some sides know more about this than others, seeing their players fall victim to the dreaded niggle or even worse, a lengthy spell on the sidelines.
Manchester United fans' initial displeasure at an apparent lack of transfer activity over the summer to fix a clearly broken squad was quickly reversed in the final two weeks of the window. Marcos Rojo and Daley Blind arrived for the relatively modest fees of £16m and £14m respectively, but the British record signing of Angel Di Maria from Real Madrid really got people talking.
Welbeck will get goals for Arsenal and it won't take him very long to find his shooting boots. £16 million what a bargain! Exciting times for Arsenal fans, if Arsenal are in a similar position to where they were last season come January and they actually decide to buy that strong holding midfielder everyone has been talking about then the title challenge is well and truly on.
You have spent £150million in a transfer window, won no competitive games as of yet, saw three of your four top defenders leave and decide to bring replacements in at the last minute, and lose 4-0 in a cup game to a League One side - good luck Van Gaal.
It's all well and good signing players who can score goals and it's not surprising that the most expensive transfers tend to be attack minded players... In what could well be the most exciting season yet, here's seven defenders who simply must perform this season and what's at stake if they don't.
Di Maria could be the key to unlock the goal scoring potential of Wayne Rooney and Robin van Persie, but he must also adapt, both to the formation and to the rough-and-tumble of the Premier League, which we've seen so many players fail to deal with.
Manchester United's American owners have been at the centre of another protest over the last week as fans took to social media in huge numbers to call for the Glazer family to sell the club and get out... But the reality is that since the takeover was formally completed in 2005, despite the questionable purchasing methods that plunged the club into debt, United have been as successful as ever.
Louis van Gaal's first foray into competitive Premier League football ended in disappointing fashion on Saturday afternoon as he watched his team slide to a 2-1 defeat to Swansea City... However, despite the initial sadness in defeat, Saturday's disappointment could be the best result for Louis van Gaal and Manchester United.
Stubborn is a word that has been used to describe the Dutchman in the past and it may well be apt here. He didn't have the personnel with the experience to implement a system dependent on defensive organisation... Was Van Gaal in the wrong by trying to start with a 3-4-1-2 formation this weekend?
After what has seemed like an eternity Premier League football is back, putting an end to talk about how awful England were in the World Cup, for four years at least... Here are five things we have learnt from the opening weekend of the best league in the world.
Every player in the Premier League is under pressure to be at their best all the time, but each club always has those one or two players whom the fans expect that little bit extra from... this season's Premier League has a few players who will need to be firing on all cylinders from the off to win over the fans and help their team succeed.