Speaking to The Mirror, however, Grant has insisted that he is determined to give manager Jose Mourinho "a choice to make" this season.
"I'm old enough and ugly enough to understand the role I'm coming in to do," the goalkeeper said. "I'm at a club that has the best goalkeeper in the Premier League, also a club that has Argentina's No.1 keeper, and there are also fantastic young keepers in the building and out on loan.
"I know what I have to contend with but I'm confident in myself, I'm settled with my own role within all of that and I'm also certain I can offer something to the club. My job is just to hold up my end of the bargain.
"I've been bought by United, so my role is to perform at a high level and conduct myself in the correct manner. That means training correctly, playing correctly when you get the opportunity and if that gives the manager a choice to make, that's my job."
Grant's career, which began in 2000, has seen him play for the likes of Derby County, Sheffield Wednesday and Burnley.