Bolt is the 100m world record holder
Jamaica's Usain Bolt clocked the fastest 200m of the year so far at the Athens Grand Prix on Sunday, to lay down a marker ahead of Beijing.
The 21-year-old cruised to a personal best time of 19.67 seconds, the fifth fastest ever.
Meanwhile, former 100m world record-holder Asafa Powell has withdrawn from next Friday's IAAF Golden League meeting in Paris.
Powell made the decision after he suffered cramp in the Rome Gala event.
Powell pulled up when he suffered cramp in his thigh 20 metres from the finishing line during a 100m race at the event on Friday.
Compatriot Bolt, who broke the 100m world record at the end of May, played down suggestions that he would soon break Michael Johnson's 12-year-old 200m record of 19.32.
He said: "It is a very hard record to get but someone will take it one day and hopefully I will be that person - maybe next year."
Cuba's Daryon Robles also sent out a warning for the Olympics, clocking 13.05 in the 110m hurdles.
It was well off his world record 12.87, set last month, but still the third-fastest time of the year so far.