The 29-year-old Argentina international has shone since arriving at Villa Park from Arsenal in September 2020 for around £16m, keeping 15 clean sheets in 38 Premier League appearances last season.
However, according to the Daily Star, United have watched Martinez on a number of occasions and are now eyeing him as a replacement for David de Gea in the number one spot should the Spaniard decide to move on.
With De Gea's contract running out in 2023, and various links of a move back to Spain over the past year, United have drawn up a list of potential replacements for the long-serving goalkeeper.
The report also states how Leeds United's Illan Meslier is another potential alternative, but that Martinez, who has been rated at £50m, is at the top of that list.
Villa's number one has a current deal that expires in the summer of 2024, and he has kept five clean sheets in 16 league games so far this campaign. body check tags ::