The 'Red Devils' find themselves seventh in the Premier League and 14 points off leaders - and rivals - Manchester City, causing Jose Mourinho to be looking at bringing in reinforcements in the January transfer window.
United's attacking contingent have struggled to find goals this season, with Romelu Lukaku, Marcus Rashford and Alexis Sanchez failing to impress up front.
According to 'The Mirror', Mourinho is targeting Austrian international Marko Arnautovic and is set to table a bid of around £50m for the forward.
29-year-old Arnautovic has been in fine form this season under Manuel Pellegrini, with five goals in 12 appearances, and both Chelsea and Everton are also said to be interested in the player.
It is understood that Pellegrini will be reluctant to sell one of his star attackers.