The former United winger also believes that by Christmas Mourinho will no longer be the man in charge at Old Trafford.
Sharpe told Press Association Sport: “[Mourinho] is the wrong man for the job.
“When he came to Chelsea the first time he was quite charming and fun, but now he just seems dour and fed up.
“He’s moaned about not signing new players and not bigging up the ones he’s got.
“The football’s not entertaining and what makes it twice as bad is that their two biggest rivals, Man City and Liverpool, do play exciting football.
“His negative style does not fit in with the expansive football that United fans want. I think he’ll be gone before Christmas.”