London - Jamaican sprinter Asafa Powell believes time is running out for him to win a global title and he is not going to waste his chance at the world championships in South Korea later this month.
Powell, who has the fastest 100-meter time in the world this season, will run at Crystal Palace on Friday - the last Diamond League meeting before the worlds in Daegu.
Olympic and world champion Usain Bolt will not be competing in London, so Powell's main concern will likely be avoiding injury.
Powell has twice won bronze at the world championships - in 2007 and 2009 - but the 28-year-old former world-record holder believes he has yet to fulfill his potential.
"Over the years I've been making too many mistakes," Powell said. "I'm a 9.7 sprinter, so if I'd been running like I should I would have been the gold medalist at these championships.
"Being in the sport for nine, 10 years, I haven't been able to match up to my expectations. My time is running out right now, so I definitely have to get a lot more serious and make sure I achieve what I feel like I deserve."
With a season-best time of 9.78 seconds - way ahead of Bolt's 9.88 - and with 2007 world champion Tyson Gay currently sidelined by injury, the worlds represent Powell's best opportunity to win a major title.
"I've been running well, posting some great times (this season)," he said. "I'm very confident, I don't have much time and I'm not going to waste my chance again."
The field at Crystal Palace will include six men who have gone under 10 seconds this season but only one, Michael Rodgers of the United States at 9.85, has got anywhere near Powell.
"It's the last competition before the world championships so I think everyone will be cautious, and (want to) get out of this competition healthy," Powell said. "The last race is always important, just to test everything and make sure everything is working fine - but you still have to be cautious, make the right decisions, decide is this smart to really go out there and run fast or just take it easy."
Bolt has already completed his preparations for Daegu, winning the 200 in Stockholm in his last outing. However, Powell admitted that he would normally expect his Jamaican team-mate to have gone faster in the 100 by this point in the season.
"Yes, it has surprised me because seeing how he has run over the years, I would have expected maybe a 9.80 or something like that," Powell said.
The London Diamond League meeting will also see Olympic champion Dayron Robles go up against David Oliver of the United States in the 110 hurdles.
Oliver is the only man to have run under 13 seconds this year, though he played down the significance of their meeting.
"Of course, everytime I run I want to win," Oliver said. "But I'm pretty sure at the world championships I'm not going to be thinking about what happened at London or Prefontaine or Shanghai - it has no bearing on what happens out there."
Competing in London for the first time will be 800 world-record holder David Rudisha.
The Kenyan will be up against Abubaker Kaki of Sudan and their rivalry could lead to Steve Cram's 25-year-old mark of 1:43.22 for the fastest 800 in Britain being broken.
"I'm looking forward (to it) because he's a tough competitor and we have been giving each other stiff competition," Rudisha said of racing Kaki. "I had some injuries at the beginning of the season but it's almost gone now and I'm picking up my shape. Hopefully I expect to run something like 1:42."
Rudisha also revealed an unusual method of preparation - watching former track greats on the Internet.
"I like watching videos of runners on YouTube, like Sebastian Coe, Wilson Kipketer, Steve Cram - those are all great athletes," Rudisha said. "I saw the way they used to run - their technique, their running style, the way they used to compete, their tactics, so I developed most of my tactics from there."
Last year, Rudisha twice broke Kipketer's world record, which had stood since 1997. Before Kipketer, the mark was set in 1981 by Coe - and Rudisha said that the man who is now head of the 2012 London Olympics organising committee had been a great influence.
"You see in the way Sebastian used to run, he was really strong, although he was small," Rudisha said. "The way he set the world record, he was really running, he was fantastic, pushing in the last 200, all the way. That is how I developed (my running)."
The London Grand Prix is the 12th of 14 scheduled Diamond League meetings this season.