Tyson Fury serenaded Wladimir Klitschko at a public workout on Wednesday, before Saturday's heavyweight world title fight in Dusseldorf.
Briton Fury, 27, will challenge WBA, IBF and WBO champion Klitschko, 39, at the 50,000 capacity Esprit Arena.
Fury dedicated his version of the Bette Midler ballad Wind Beneath My Wings to the Ukrainian, who was ringside.
"I'm not coming to Germany to win on points, I'm going to do a demolition job on Wladimir," said Fury earlier.
In response to Fury's latest antics, Klitschko said: "Tyson Fury belongs on Britain's Got Talent.
"I don't want to compete with him in a singing contest. I definitely won't make it. He has better talent than I do in singing."
Klitschko, a two-time heavyweight world champion, has not been beaten since 2004 and has had 27 world title fights and made 23 successful defences.
Manchester's Fury is unbeaten in 24 professional fights, with 18 knockouts, is challenging for a world title for the first time and is a heavy underdog.
"I don't fancy getting a points decision in Germany so I'm expecting a knockout victory," Fury added. "Saturday night is glory night for Tyson Fury.
"All his past opponents came to Germany believing they were going to lose. They came for money but money isn't my motivation, winning is my motivation.
"You can't teach an old dog new tricks. He's almost 40 and what he hasn't shown, he hasn't got. I know what's coming.
"He's going to wish he'd never met Tyson Fury, but I can't make him more nervous than he already is - he's shaken.
"Not only am I winning, I'm going to win it in style. And then I'll sing everybody a victory song."
Fury, a former British, European and Commonwealth champion, seemed relaxed at a bizarre event in the departure lounge of Dusseldorf airport.
The challenger arrived half an hour early for his workout and chatted freely with the assembled media, before launching into an impromptu song. While Fury was singing, Klitschko, waiting for his turn in the ring, looked unimpressed.
"I thought I'd seen it all but I was wrong. Tyson Fury is very different to anything I've seen before" said Klitschko, who has won 64 of his 67 professional encounters, with 53 knockouts.
"He is a very challenging individual, both in terms of his manners and his boxing. He's a lot of things in one person.
"He's taller than me, younger than me, has a longer reach, is heavier, can switch from orthodox to southpaw, has a variety of punches, is flexible and has never lost.
"He's going to be very ambitious and I'm expecting it to be one of the most difficult fights I've had. But everybody has a plan against me, has seen something nobody has seen before. I've heard it a lot.
"The reality is going to come up and at the end of the day it's going to be a cold welcome to big-time boxing"
Against Klitschko, Fury will wear a pair of boots presented to him by the champion's former trainer Emanuel Steward, before he died in 2012 - and the Englishman will also be buoyed by the presence of his father, John, in his corner on fight night.
Fury Sr was jailed in 2011 for gouging a man's eye out but was released this year and has received special dispensation to attend.
British pop legend Rod Stewart will be performing before Saturday's fight, which is expected to attract a healthy contingent of travelling British fans.