With the current performance of Manchester United this season in the Premier League, Manchester United can't beat Arsenal at Old Trafford. Arsenal will not want to drop another point in the Premier League because it will affect them in the race for this season's Premier League title. Arsenal has already made the same mistake they made last season that cost them the Premier League when Aston Villa defeated them at Emirate Stadium.
Manchester United this season has been a disaster, from when the Champions League Competition kicked off till date, they have seen nothing but up's and downs so far. I remember Old Trafford as one of the best places they convert and take points from opponents, but doing same thing this season I believe will be difficult to achieve.
They drop points and one can go ahead to say that, it's over for them in the English Premier League Competition. They have to do all they can to make sure that they emerge as winners of this Competition.
They also made same errors against Tottenham Hotspur during the weekend but glad they defense or should I say the entire squad was able to defend the gamw until the final whistle was blown.