Sanya Richards-Ross, who won gold in the women's 400 metres on Sunday, returned to Olympic Stadium the following day and advanced to the semi-finals of the 200 metres. She won her opening race in 22.48 seconds -- the fastest time in any of the six heats.
Asafa Powell ran the fastest 100 meters in the world this year.
Not even Usain Bolt could overcome a big American lead as the US men sprinted to a convincing victory over Jamaica in the 4x100 metres relay at the IAAF World Relays in Nassau on Saturday.
With no Russians, few stars and the sport engulfed in a doping crisis the world indoor athletics championships begin this week with officials holding their breath and eager to put the spotlight back on the track.
Olympic 200 metres gold medallist Allyson Felix has chosen to run the 400 metres at next month's world championships, her coach told Reuters on Wednesday.
Jamaica won the showcase 4x200 metres relay without Usain Bolt as their American rivals dropped the baton at the IAAF World Relays in Nassau, Bahamas on Sunday.
Tyson Gay overcame Olympic bronze medallist Justin Gatlin's quicker start and sped to the year's fastest 100 metres, clocking 9.75 seconds at the US trials for the World championships on Friday.
Botswana's Nijel Amos laid down a marker ahead of next month's world championships by winning a highly-anticipated 800 metres showdown with Kenyan Olympic champion David Rudisha at the Anniversary Games on Saturday.