Jeremy Wariner safely negotiated the opening round of the 400m, breaking as he hit the line first in his heat in 45.10.

His compatriot Lionel Harry, third in the US trials, was not so lucky, pulling up at 350m and limping off with suspected cramp. In the pool for the 4x400m, his place may now be in jeopardy.

German champion and European indoor silver, Bastian Swillims, also failed to advance, despite setting a personal best 45.44.

Other than that, it was a morning without incident for the quarter milers, the track giving some indication of what to expect when Chris Brown of the Bahamas effortlessly came within 0.02 of his PB in the first heat.

Four national records, seven PBs and 12 season’s bests were a rich harvest for just one round, leading to speculation about what Wariner might do when the running gets serious.

LaShawn Merritt and Angelo Taylor make up what could well be an American clean sweep while Gary Kikaya (COD), Ricardo Chambers (JAM), Tyler Christopher (CAN), Sanjay Ayre (JAM) and John Steffensen (AUS) encountered no problems.

Osaka 2007 News Team/mb