Usain Bolt's plans for an assault on Michael Johnson's 400 metres world record are likely to go on hold until after the London Olympic Games.
The world's fastest man will compete over 300m in the Czech Republic on May 27, but the Jamaican will delay a bid to dip below Johnson's world record of 43.18 seconds until after the 2012 Games.
"I think the 400m is somewhere in the future but hopefully after 2012," said Bolt, who will bid to take Johnson's 300m best at the Golden Spike meeting in Ostrava.
The 100m and 200m world record holder often begins his season running 400m races to build up his fitness, and has a three-year-old personal best of 45.28s. However he has not taken the event seriously so far.
And he is likely to aim to defend his 100m, 200m and 4x100m relay Olympic titles before turning his attentions to Johnson's record.
"The 400m is painful," said Bolt, who will earn $US30,000 if he beats Johnson's 300m world record of 30.85s, set at altitude in Pretoria 10 years ago.
Bolt, who will also appear at the IAAF Diamond League meetings in New York on June 12 and Paris on July 16, revealed his preparations for the summer are progressing satisfactorily.
"Training is going well," he said.
"I am getting ready for the summer season. My early races in Jamaica have been good so I think I am where I need to be at this time of year."
"There is still a lot of work to be done in the next two months but I am getting there."
Of his targets in a year without any global championships, Bolt added: "I just want to keep winning and stay injury free."