Current number two Dean Henderson - standing in for David de Gea after the birth of his child - is keen to nail down a regular starting role for United and would be ready to leave if he is not guaranteed the number one jersey for next season.
The England international got off on the right foot as he kept a clean sheet in Sunday's 2-0 win at Manchester City, but Ole Gunnar Solskjaer is understood to be looking for a new man in between the sticks regardless amid uncertainty surrounding the future of De Gea.
As a result, Sky Sports News claim that United have been scouting Atletico number one Oblak for over a year and would love to welcome the Slovenia international to Old Trafford, but finances could prove to be a problem.
The report adds that Oblak - previously linked with Chelsea - possesses a £103m release clause in his Atletico contract, so United could instead opt to swoop for AC Milan's Gianluigi Donnarumma or Lille's Mike Maignan.
Oblak has kept 12 clean sheets in 25 La Liga games this term, shipping just 17 goals as Atletico sit at the top of the rankings.