Wariner won the Olympics 400m title in Athens, in 2004, and followed that with World Championships wins in 2005 and 2007.

The 27-year-old, a key player in the US Olympic and world 4x400m relay wins, tore a ligament in the second toe of his left foot while training in July.

Right now my focus is to get healthy, prepare for next season, and try for my second 400m Olympic gold, he said.

The injury will not require surgery but may take 12 weeks to recover from.

Wariner, the world's top-ranked 400m runner in 2010, has been plagued by minor injuries this season.