George Foreman has dubbed Lennox Lewis as "the best since Ali", ahead of the bout between Lewis and Mike Tyson in Memphis on Saturday.

Defeats by both Oliver McCall and Hasim Rahman rank as low points in Lewis' career, but Foreman believes the British boxer has learned his lesson.

"I think the defeat by Rahman in their first fight was a wake-up call for Lewis," Foreman said in the Daily Mirror.

"He will not fall asleep like that again."

Lewis has since avenged both those defeats and Foreman is high in his praise of the London-born fighter: "Lewis does not have to be cautious against anyone.

"He is an excellent boxer, the best since Ali himself."

Lewis' previous fights have shown him to be a cautious fighter, sometimes to his own detriment.

This was particularly the case in Lewis' first drawn meeting with Evander Holyfield at Madison Square Garden, when Lewis had the better of the fight but failed to finish his opponent off.

While he has belief in Lewis' abilities, Foreman acknowledges that Tyson could use his relatively small stature to his advantage.

"Tyson has an excellent chance.

"He has been more successful against taller guys than any heavyweight in history.

"He can beat Lewis if Lennox plays around with that old cautious style.

"Lewis has to jab a few times then go for the knock out."