London - US sprint star Tyson Gay is open to converting from the shorter events of the 100 and 200m to the lung-busting 400m discipline, with one eye on the US relay team for the 2012 London Olympics.

Gay, the world leader in the 100m in the absence through injury of Jamaican duo Usain Bolt and Asafa Powell, admitted that he had clocked a sub-45 second run in the one-lap event this season.

And he added that he would love to have the chance to run the 4x400m relay with the likes of US team-mate and two-time former 400m world champion Jeremy Wariner.

"I combine the 100m and the 200m, and that is very difficult to do," said Gay, who won double gold at the Osaka world championships in 2007 before Bolt wrapped up double sprint titles at the 2008 Beijing Olympics and Berlin worlds a year later.

"Training has to be well balanced to be successful in both events. I do reflect upon the 2012 Olympics, but not in clear terms yet.

"I still have to decide on the distances that I want to run. But I definitely want to run more 400m races in the years to come.

"I want to make the USA 4x400m (relay) team. One day I want to be part of a team with Jeremy (Wariner) and the others, that is an experience that I’ve never had before."

Gay added: "I did run 44.89sec this year, but I can run faster in my next 400m races. Of course the 400m is a tough event: it makes you feel dizzy in the head and miserable in the stomach, but I want to try it. I'm a tough guy as well."

The American's aim for Friday's meet, the second of two finals of the inaugural 14-meeting Diamond League series, is to better his 9.78sec world lead and possibly his personal best of 9.69, the second fastest time ever run.

And Gay said the absence of Bolt and Powell from the field would detract neither from the show nor his efforts.

"Of course you need strong competition to become a better athlete. To me it's not so much about the pressure that it generates, but because you want to win races," he said.

"If the conditions are good, I think I'm always able to execute well."

Gay emerged from the rather large shadow cast by Bolt with a victory over the 100 and 200m world record holder in Stockholm earlier this month - it was Bolt's first defeat since a pre-Beijing loss, also in the Swedish capital.

"The past two years journalists kept on asking me whether it was possible to beat Usain Bolt in the 100m. Since Stockholm nobody ever asked me that question again," joked Gay.

"I had two minor setbacks this year and I feel that there is still more to come. I am not entirely satisfied with what I've performed so far.

"It's true, I am the fastest man in the world this year but mentally and physically I feel capable to improve my personal best (9.69) if conditions are fine.

"That is what I'm aiming for on Friday. Don't forget that Stockholm was only my second 100m of this season."