The 32-year-old has won 57 caps for his country and was named in Fabio Capello's provisional 30-man squad for the global showpiece in South Africa on Tuesday.
However, the former Leicester and Liverpool forward has struggled for first team opportunities under Martin O'Neill this season - netting just five goals for Villa in all competitions - leading many fans and pundits alike to question his inclusion in the national party.
Heskey is expected to be make Capello's final 23-man squad, with the powerful front-man viewed - along with Peter Crouch - as the perfect foil for the craft and pace of fellow strikers Wayne Rooney and Jermain Defoe.
And Gullit, who featured for the Netherlands at the 1990 World Cup, insists Heskey still has a lot to offer the Three Lions, but doubts whether he fully believes in his own ability.
Speaking at the launch of the Budweiser Prediction Panel, he told FourFourTwo.com: "Heskey has had a difficult season. I know a lot of people doubt him because he lacks goals, but that is because he doesn't have that confidence.
"But he has got it in him. He's too nice, he has to forget Mr Nice Guy.
"I played against him, he's a strong, powerful player. The first time I met him I told him after the game: 'you have everything, you're going to be one of the best'.
"I sometimes doubt that he knows that. I think he is too doubtful about himself, and because of that he misses chances."
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Ruud Gullit is part of the Budweiser Prediction Panel, encouraging football fans to make 2010 FIFA World Cup predictions at www.budweiser.co.uk/predictandwin to be in with a chance of winning fantastic prizes including £100,000.
