LONDON (AFP) - - Jamaican sprinter Asafa Powell has warned his Olympic rivals that he is back to his best after the shoulder injury that threatened to wreck his Beijing gold medal challenge.

Powell expects to provide further evidence that he has made a complete recovery from a shoulder problem which sidelined him for several weeks when he runs in the London Grand Prix on Friday.

The 25-year-old laid down a marker by recording a season's best of 9.88seconds on Tuesday to defeat fellow Jamaican and world record holder Usain Bolt.

Powell, who has clocked times under 10 seconds 37 times in his career, has arrived in England full of confidence ahead of a meeting that will play a key role in his preparations for next month's Games in China.

"I got very nervous with the shoulder injury and I thought to myself my Olympic Games is over," Powell said.

"Now I'm still running 9.88secs so I'm content. I forgot what it takes to run a fast race - I was trying too hard and I do better when I don't try too hard."

Powell took a cheeky swipe at Tyson Gay's withdrawal from the event with a hamstring injury when he appeared to hint that his rival was hiding from racing aganst him.

"If you know someone is better than you, hiding from them won't make it better," he said "To run together as much as possible is no problem.

"Tyson not running, makes no difference to me."

With Gay ruled out, Powell has the perfect opportunity for another morale-boosting victory.

But he admitted success in London would mean nothing unless it is followed by gold in Beijing.

"It won't mean a thing, what is important to all of us is what happens in Beijing next month," Powell said.

"Going away with two wins - I'm used to that, but it won't make a big difference to me because anything can happen at the Olympic Games."

Despite Gay's absence from Crystal Palace there are still several sub-10 second sprinters in the field, prompting the suggestion Powell could claim back his world record.

"Of course it's possible but I've never once gone onto a track thinking about a world record. So I always surprise myself when I do it," he added.

Bolt, despite being the world's fastest man, still has to decide whether to run the Olympic 100m or compete over 200m which he admits is his favourite event.

The 21-year-old former world junior champion's decision could come after his outing over the half-lap distance at the London meeting's second day on Saturday.

Bolt, who will be defending his London title, said: "My coach has still given me no clue. It's a good thing, making me prepared to do either event but the important thing, whatever I do, on my mind is the gold medal."

The 6ft 5in sprinter, after running 19.67secs over 200m for the world's fifth fastest ever time a fortnight ago, believes coach Glen Mills will definitely give his decision after watching his form at the Palace.

"If the weather's good I can run a fast time but a personal best's not a factor for me," said Bolt.

"I need to improve some features of my race before Beijing."