Welbeck has been linked with a move away and could leave United with just the two strikers.
Manchester United forward Danny Welbeck has been strongly linked with a move away from Old Trafford during this transfer window - with Tottenham rumoured to be one of many clubs interested in the player.
So far during Louis van Gaal's tenure at Old Trafford, the side have been adopting a 3-5-2 system - with Wayne Rooney and Robin Van Persie the preferred attacking duo to lead the line.
United also seem close to sending Mexican forward Javier Hernandez out on loan to Real Madrid - and if Welbeck were to leave, the club would have just the two recognised strikers for the season ahead - though it isn't beyond the realms of possibility that van Gaal may put his faith in a young striker from the youth team, but that would be a big call even for someone like the Dutchman.
But with Hernandez seemingly on the brink of leaving Old Trafford for the season, and still the possibility of Welbeck leaving the club, there is still the 'what if?' question surrounding Van Persie and Rooney. That is - what if they get injured?
Just two strikers available when you're playing a two striker system is asking for trouble some would say. There is also the point that United may try and bring in another forward before the deadline, but if United were left with two strikers, surely they couldn't start both forwards in every game?
Playing a 3-6-1 formation - or any variant when it comes to the midfield - would leave the middle of the park quite congested, where as playing with a back four and a five in midfield is seen a lot both in the Premier League and Europe.
With Wayne Rooney the captain, and Robin Van Persie a high profile forward who would walk into most sides in the Premier League, it could mean a very difficult decision if there were a change of system.
The fact is, United need at least a third recognised striker during this period and it would represent a big gamble otherwise. Whether Welbeck remains as the third forward remains to be seen.