By Martyn Herman

LONDON (Reuters) - Former champion Wladimir Klitschko said he is obsessed with regaining his world heavyweight crown and he would wait for as long as it takes for his re-match with Britain's Tyson Fury.

The fight has been fixed for Oct. 29 in Manchester, having been postponed in July when Fury suffered an ankle injury, although doubts have been raised about whether it would go ahead after Fury was charged with an anti-doping violation.

Fury, who denies the allegations, caused a huge shock when he deservedly took a unanimous points victory over Klitschko in Dusseldorf last November to de-throne the Ukrainian who had ruled the heavyweight division for a decade.

Klitschko, who has since turned 40, said that defeat by the 28-year-old so-called Gypsy King had motivated him to get better.

"It was actually a great experience for me," he said at a news conference in London at which Fury failed to show.

"I always say that when one door closes another opens. I've gained out of it and have great motivation and I'm obsessed with the goal to get my titles back.

"I'm patient. Even if it doesn't happen in October, I will wait. Time will eventually run out for Fury," he added.

Fury's promoter Frank Warren said there were no "contractual" problems surrounding the fight and that it would go ahead -- saying UK Anti-Doping's independent tribunal into allegations of Fury testing positive for a banned substance would take place after the re-match.

"The only problem today is Tyson's car," Warren said.

Klitschko, who will be fighting to reclaim the WBO and WBA belts after Fury was stripped of his IBF crown because he did not fight a mandatory challenger, laughed off Fury's no-show.

"Maybe he's here as the Invisible Man," he said.

"It doesn't matter to me whether he shows up singing or as Batman or the Invisible Man, I'm ready for everything. I have my goal and I'm obsessed with that. I'm preparing well and just hope that he shows up in the ring in October."

He suggested Fury would be a better opponent second time round, even if he is clearly not a fan of the Britain who he described as a "lunatic" for homophobic, sexist and anti-Semitic comments he posted in a video posted online this year.

"I expect him to be better this time and I'm going to better and going to be different," Klitschko said. "We fought previously and know each other well. I hope he's training well because I want to fight the best Fury."

Unbeaten Fury, who has courted controversy throughout his career, was charged with a doping offence by UK Anti-Doping (UKAD) on June 24 after a urine sample taken nine months before he beat Klitschko showed traces of banned substance nandrolone.

However, Fury's legal team said the result of tests on the samples in March and May 2015 were contradictory and launched High Court proceedings against UKAD.

A provisional suspension was lifted pending the result of an independent hearing.

(Reporting by Martyn Herman, editing by Pritha Sarkar)