The Mirror says Giggs' family say he may walk away from his football career over allegations he had affairs behind his wife's back.
A family friend said: "We fear that Ryan will go now and just call it a day once and for all.
"The feeling is another year is just one too many for him to be bothered with. A lot of supporters have lost a lot of faith in him, and Ryan doesn't need the hassle of taking stick from away fans."
A club source said: "Concerns are growing. Sir Alex [Ferguson] is willing to cut Ryan some slack and give him extra days off to clear his head."