The injury to Luke Shaw is serious and the Red Devils are now actively looking to sign a new left back in the winter transfer window.
Reports in the media (Daily Star) suggest that Manchester United will make a $23.2m bid to sign West Ham full back Aaron Cresswell.
The 25-year-old England international has started the season brilliantly with the Hammers and has the talent to effectively replace the former Southampton star at the Old Trafford.
This season, in 6 Premier League appearances Cresswell has set up 2 goals for West Ham United. His performances have been pivotal in helping the side earn victories against Arsenal, Liverpool and Manchester City.
Last season, Aaron netted two goals and provided 4 assists and the stats suggest that he is highly effective in the attack as well.
There is still a few months before the start of the winter transfer window. If Rojo or Blind can perform well in the left full back role then perhaps Van Gaal will have no real need to move for Cresswell.