Judo gold medal contender Mayra Aguiar admits she was a nervous wreck during her Olympic Games debut in Beijing four years ago.

The 78kg class world No.1 says experience and maturity have armed her with new-found confidence ahead of the London Games.

"The difference now is that I am much more mature," the Brazilian said on Wednesday. "I'm still only 20 years old but I'm a different athlete to the one in Beijing.

"Back then I didn't know how to handle the pressure and I just wanted the competition to end. I didn't stop crying when it was over because I was finally free of that burden."

Having been eliminated in the preliminary round in Beijing, Aguiar quickly turned around her fortunes.

In 2010 she won silver at the World Championships in Tokyo followed by bronze at the same event in Paris last year.

A series of impressive results, including the Paris Grand Slam title earlier this year, catapulted Aguiar to the top of the world rankings.

But her experience has taught her that there is a fine line between confidence and arrogance.

"I'm not going to go there thinking that I'm going to win just because I'm No.1 in the world," Aguiar said. "I have a good chance, but so do my rivals."

Aguiar said a disadvantage of her success had been the increased homework being done by rivals to find her strengths and weaknesses.

But she warned other medal contenders she was working on diverse strategies to catch her opponents by surprise.

Brazil's judo Olympic squad will leave for London on July 16 with competition scheduled to begin on the 28th.