Man United entered the game off the back of two defeats in their last three Premier League matches, but they managed to turn around a two-goal deficit to beat Atalanta BC in the Champions League on Wednesday.
The 20-time English champions were booed off by their own supporters at the interval, and Ferdinand took to social media to criticise his former side for their display.
The pundit insisted that Ole Gunnar Solskjaer's team will "pose a threat" due to their strong attacking players, but the 42-year-old cannot believe how easy sides can open up the Red Devils.
Man United are next in Premier League action away to Tottenham Hotspur next weekend. body check tags ::