Former Olympic champion Michael Johnson has urged Usain Bolt to try and break his 400m world record.
Writing a new column for the London Times, as the countdown to the Games in London begins, the four Olympic gold world record holder over the distance said the 400m challenge could provide the Jamaican, who holds the world record in the 100m and 200m, the motivation to keep running beyond the 2012 Olympics.
"It would be incredible to see someone hold the world record at 100 metres, 200 metres and 400 metres and that's where his motivation could come from after London," said the former American sprint ace.
"I'd like to see him compete at 400 metres. I think he could break [my] world record [43.18 seconds, set in 1999] if he did.
"I certainly expect him to repeat as Olympic champion in the 100 metres and 200 metres and if he turned his focus at that point to 400 metres, it could keep him motivated and keep him in the sport longer," he added.
However, Johnson, the only male athlete in history to win both the 200m and 400m at the same Olympics (at Atlanta in 1996), indicated Bolt may prefer switching to the long jump.
He said he had spoken with Bolt about the prospect of him running the 400m, but it seemd the Jamaican, who became the first man to win three sprint events at a single Olympics since Carl Lewis in 1984, and the first to set world records in all three at a single Olympics - 2008 Beijing - is not prepared to go through the ardous training needed to run the 400 metres.