London - Lennox Lewis says his heart wants David Haye to win but his head says Wladimir Klitschko will beat the Briton in Hamburg on Saturday night.
The former heavyweight champion, who once beat Vitali Klitschko, said on Friday Haye had the talent and the punch power to knock out the IFB and WBO champion in their unification fight.
"And to win he has to knock him out. If it goes to the judges, Wladimir will win."
The 45-year-old Lewis feels Klitschko has a better jab than Haye, a wealth of experience and one of boxing's top coaches, Emanuel Steward, in his corner.
But Haye can cause the Ukrainian problems. "My heart says David, but my head says Wladimir," Lewis told the website Boxrec.com.
"The reason is that Wladmir has a good jab, good experience and a great trainer in his corner.
"However, if there is one fighter who can unsettle him -- and he has done so already with what he's been saying -- it's David Haye."
Haye's team have complained about the referee, Henaro Hernandez,who has overseen four of Klitschko's world title bouts, including his 2003 loss to Corrie Sanders, and Lewis says they are right to object.
"As far as the referee goes, I would be doing exactly the same as Haye did," said Lewis. "But David Haye should allow his own judges, his fists, to decide the fight."
Lewis retired in 2003 having beaten Vitali Klitschko. He also knocked out Mike Tyson in June 2002 and held the WBC and IBF belts.