Yeah that's true because Fulham has a very low performance since last season till now, and they have played 9 matches and won only 4, lose three matches and draw two matches, although considering this record they are good but not good enough to beat Manchester United because irrespective of how Manchester United has been on a serious poor performance this season but I don't think Fulham stance on any chance of winning them. However even if they are playing from home, there advantage will not be enough to win the Manchester United.
I'm surprised you have that much faith in Manchester United. Manchester United have been very poor, any team at all can win them.
Manchester United are the favorite to win obviously but playing away from home at a time when they're not in good form is a pretty disadvantage. Also, an early kickoff can be tricky.
When it comes to Manchester United I try to avoid them when I'm betting because they're pretty inconsistent. Fulham is not in top form but they can harm United.