By Caroline Cheese BBC Sport Online at Wimbledon

At the age of 13, Xavier Malisse was considered as good at football as he was at tennis.

To Greg Rusedski's detriment, he chose to ply his trade at the latter but the offbeat personality, along with the ill-conceived slicked-back ponytail, would not have been out of place at the World Cup.

Through to the quarter-finals of a Grand Slam for the first time, Malisse is only now beginning to fulfil a talent that has been bubbling under since he turned professional in 1998.

By beating Rusedski, who so convincingly disposed of Andy Roddick in the previous round, he sounded a warning that he is no longer a player to be dismissed as hot-and-cold.

Player profile: Xavier Malisse

Twice down a set, he refused to buckle and demonstrated a newfound determination that saw him triumph in circumstances where many might have crumbled.

Once more famous for his changing hairstyle and a failed relationship with Jennifer Capriati, Malisse's results early in his career were recognisable only by their inconsistency.

Capable of troubling the very best, he very often lost easily to players who had only a modicum of the talent at the Belgian's disposal.

But Malisse finally tired of being the most talked-about underachiever in tennis at the end of 2000 when he finished the year outside the top 100 once again.

"I told myself I got to give myself a shot at it," he said.

Relief for Xavier Malisse after his victory

"Everybody was talking and saying I had talent, but I wasn't really working hard.

"I went to Florida in November 2000 and practised a lot, just tried to do something different."

Since that decision, three coaches have come and gone, including Tim Henman's former coach David Felgate.

He is now under the tutelage of Craig Kardon, former coach of nine-times Wimbledon champion Martina Navratilova and Mary Pierce.

"They're all women," commented Malisse of his coach's former charges.

"But I have a ponytail so it looks like a woman."

Nonetheless, the results have continued to improve.

In the past year, he has proved to be the scourge of British players, beating Henman at the US and French Opens and now ending Rusedski's hopes at Wimbledon.

He claims it is nothing personal.

"It doesn't matter which nationality," he said.

"I think you go out there and give it a shot. There's a lot more years - they can get back at me."

Not if he continues to play as he did against Rusedski.

Laid-back on and off the court, he can look like he has completely misjudged a shot, only to use fancy footwork to dance around the ball and unleash a fierce passing shot.

"I feel good on all surfaces," he said.

"Maybe I wasn't expecting to get to the quarters, but I feel good on grass and every match is going better and better."

Greg Rusedski finds the going tough

Rusedski was dismissive of Malisse's chances of winning the title, and after years of the Belgian producing near-perfect tennis only to self-implode when expectation grew, you can see why.

But on this Wimbledon run, he has beaten fifth seed Yevgeny Kafelnikov and an in-form Rusedksi in consecutive matches, the only sets he has dropped all tournament coming against the Briton.

He will be up against one of two serve-volleyers in the quarter-finals, Richard Krajicek or Mark Philippoussis, both of whom would do well not to underestimate a newly focused 'X-Man'.