Ronaldo, 28, signed a contract extension at Real Madrid last night to keep him at the Bernabeu until 2018 but has hinted he wants to end his career at Old Trafford.
Gaspar said: "I think an athlete like him can easily carry on until 33.
"In fact, in his case, I reckon that, barring anything untoward, he will be at the peak of his powers even longer, until 35.
"He's a super-athlete, way above the average in that sense, and he's also a top professional who takes perfect care of himself and doesn't miss a trick when it comes to his diet and recovery time.
"Real Madrid knows what they are doing, it's not a gamble, and Ronaldo will be at the top of his game until the end of his contract."
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