Last updated on .From the section Judo

Britain's former world champion Craig Fallon has been knocked out of the World Championships in Paris in his first fight.

The 28-year-old, who won the tournament in 2005, lost to Martin Ivanov of Bulgaria by ippon, the highest score possible.

"I didn't expect him to be that strong," Fallon told BBC Sport.

There was greater success for Fallon's Olympic rival Colin Oates, who finished a career-best fifth.

Judo scoring system The highest scoring move is ippon, for 10 points, which can be executed by throwing an opponent flat on their backs with control and force, holding them down for 25 seconds or forcing an opponent into submission through an armlock or stranglehold.

Below ippon is waza-ari, for five points, which means throwing an opponent on their back without the force or control of the ippon. Alternatively, holding a rival down for 20-24 seconds.

The yuko, for one point, is awarded for throws where the opponent doesn't land flat on their backs (i.e. on their side), or a hold for 15-19 seconds.

Oates, who had already secured a European bronze medal and national title this year, defeated the world number 13 David Larose on his way to his bronze medal match-up.

But world number four Musa Mogushkov was a step too far, as the Norfolk-born judoka lost by ippon, when he was thrown flat on his back, to place outside the medals.

Oates' relative success was in stark contrast to Fallon, who said: "I got caught at the end when I was dominating. I started well but the strength difference soon kicked in."

Midway through the bout, a clash of heads meant Fallon required medical attention and afterwards he reflected: "It's not great to have interruptions during a fight and have the medical staff come out," he

"It's never good to go out on your first fight at the Worlds but I'll see how it goes and pick things up."

Since his return to judo earlier this year, Fallon has struggled to demonstrate the consistency selectors are looking for ahead of the 2012 Olympics and British Judo head coach Patrick Roux said it is Oates who is in prime position for the one -66kg spot for next summer's Games.

"He is ahead [of Craig Fallon]," Roux told BBC Sport. "But players have to stay on their toes all the time. I want to maintain positive competition between players right up until the European Championships in 2012."

Meanwhile, European Under-23 champion Ashley McKenzie lost his third fight to fourth-ranked judoka Hirofumi Yamamoto in the under-60kg category.

In the same weight group, James Millar went out in the fourth round to European champion Georgii Zantaraia.

Britons Danny Williams (-73kg), Sophie Cox (-52kg) and Gemma Howell (-57kg) take to the mat on Wednesday.

The World Championships, running from 23-28 August, serve as an important marker ahead of the 2012 Olympics as judoka fight for selection.

These championships are expected to be more difficult than next summer's as two players from each nation are allowed to compete in each weight category, rather than one.