David Haye's trainer insists the first defence of his WBA heavyweight title against John Ruiz will be the hardest of his career.

Haye took the title from Russian giant Nicolai Valuev with a hit-and-move policy but Adam Booth knows that similar tactics will not work against a spoiler like Ruiz.

And the trainer believes Haye will have his work cut out to look good against the former champion, who has been in with the best in the division for more than a decade.

"I've said all along that the hardest fight of David's career is John Ruiz, I've no doubts about that," Booth told Sky Sports. "Maybe Vitali Klitschko would be harder, but Ruiz, because of his style, makes it the hardest of David's career.

"The John Ruiz threat is real, it's not imaginary, because of his style, because he's good at making fighters look bad, and he's good at getting people into range and trading with them.

"Everybody knows that David likes to box long, so that's why this is a hard fight for David.

"We knew that David could run away from Valuev and win the fight, but you can't run from John Ruiz becuase he'll just chase you down.

"And if you run, the less power you've got in your shots. With Ruiz you have to bang hard and bang for 12 rounds so we know it's not a question of running from Ruiz, it's question of getting his respect and hurting him early, and domination the fight from the centre of the ring."

However, Booth is confident Haye has the tools to win a very different fight from the one that saw him win the title last November.

"David is a natural fighter, he loves getting in there close and trading blows," he added. "The closer he gets to the fight happening the more focused and narrowed down his mind gets.

"I see it as a hard night, but a win for David."