European Champion Kevin Borlée ran in the third series.
He ran a strong race and finished second with a time of 44.77, just three hundredths of a second slower than his own personal record of 44.74 seconds and six hundredths of a second slower than his brother Jonathan’s Belgian 400 metres record.
Only the American LaShawn Merritt was faster, finishing the race in 44.35 seconds.
Meanwhile, Jonathan Borleé completed his race in 45.16 seconds, four hundredths of a second slower than the winner Kirani James of Genada.
The semi-finals will be run on Monday from 1pm Belgian time. The final is planned for 2:45pm.