Sharpe, 41, says RVP's movement allows Rooney the space to pull the strings for the Dutchman, who has hit 12 top-flight goals for the league leaders already this season.
He told the Daily Star: "Van Persie has been an unbelievable buy for United and you can see Rooney is enjoying playing alongside him so much.
"Their partnership is growing and the understanding is getting better with each game.
"And that is why I see United winning the title, because they are only going to get better. Yes, City and maybe Chelsea will have a say - but these two players are irrepressible.
"Van Persie being up top has taken the burden off Rooney and given him more time and space."