Olympic and world champion Jeremy Wariner is convinced he will break Michael Johnson's long-standing 400 metres world record at this year's Beijing Olympics, if not before.

The 24-year-old Texan has dominated the men's one-lap event for the last four years and the world mark of 43.18 seconds set by Johnson, his mentor and agent, at the 1999 World Championships is firmly in his sights.
"I'm looking forward to defending my title and hopefully breaking the world record," he said on Monday.