Reports had previously suggested that the 38-year-old, who has scored one goal in seven appearances this campaign, had told friends he will call an end to his career for the second time next summer.
But Sir Alex believes the former England international has no such plans and that he would be the first person Scholes would consult if he did.
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And the United boss was also keen to quash similar speculation about Ryan Giggs and Rio Ferdinand, stating that any rumours stem simply from the club’s contract policy.
"Ryan could play for another year or two. Rio has been terrific,” he added. “The speculation comes from our policy of only giving older players one-year contracts."
Meanwhile, Sir Alex was in jovial mood when discussing Cristiano Ronaldo’s first return to Old Trafford since leaving United in 2009.
Ronaldo will return to his former club when Real Madrid face the Red Devils in the last 16 of the Champions League and the United manager was in good spirits ahead of the encounter.
"It is in his contract he can't play against us," he joked. "It would be a disgrace if he played.
"It will be fantastic to have him back."