Trinidad-born teenager Kerron Clement broke Michael Johnson's 10-year-old 400 metre indoor world record with a time of 44.57 seconds.
Clement, running for the University of Florida at the NCAA indoor championships at Fayetteville, Arkansas, on Saturday, was 0.06 seconds faster than the time of 44.63 that Johnson ran in Atlanta on March 4 1995.
Second-placed Terry Gatson ran what would have been an NCAA record time of 45.29 but still finished some seven metres behind Clement, according to the International Association of Athletics Federations (IAAF) website.
