McLaren star Hamilton is convinced he can land his second championship following his runners-up place in Korea.
That left him 21 points adrift of Ferrari leader Fernando Alonso with just the Brazil and Abu Dhabi GPs to go next month.
But 1992 champ Mansell fears Hamilton may pay a heavy price for a few out-of-character 'misjudgments'.
The 2008 king, 25, confessed last weekend family illnesses and a personal falling out with his dad and manager Anthony had affected his performances. Hamilton crashed out in Italy and Singapore and two weeks ago wrecked his car in first practice in Japan, where he finished fifth.
Mansell said: "A few misjudgments have crept in this year and I'd like to give him the benefit of the doubt and say he's better than that.
"So there are obviously a few things going on inside his head where he's not in sync with himself.
"Whether you have got mirrors or not you know exactly where you are on the circuit and where you are racing someone else. He's been caught out a couple of times but if he's the class act I'm sure he is, he won't repeat that and will be better for it."
Mansell is convinced Mark Webber can still rule supreme in his Red Bull and become the first Aussie to land the world title since Alan Jones in 1980.
Spaniard Alonso overtook Webber, 30, in the championship on Sunday to move 11 points clear.
But the Aussie blamed himself for his first accident of the season on lap 19 that opened the door for Alonso to claim his fifth victory of the campaign.
Mansell added: "I still think the title's there for Mark Webber to lose now and I don't think he will.
"There has been stuff going on within the team all year but he has demonstrated he is strong of character and strong of mind.
"Mark is a class act as he showed when he came back from that accident in Valencia. In years gone by anyone thrown through the air like that would have been hospitalised or dead.
"Then you think of the accident he had on a mountain bike, hitting the car head on and breaking his leg and yet he came back from that, too.
"Mark is not taking any risks. I have to commend him because he's been so professional by finishing second and taking the points.
"Alonso is a brilliant driver but for me Ferrari lost focus by publicly demonstrating that their drivers basically don't get on."
Source: The Sun
