The top three runners in each of the initial eight heats automatically qualified for the second round.

The next ten fastest runners from across the heats also qualified.

Before the competition records were as follows: All times shown are in seconds.

The first 3 athletes in each heat ( Q ) and the next 8 fastest ( q ) qualified for the quarter-final.

The first 3 athletes in each heat ( Q ) and the next 4 fastest ( q ) qualified for the semi-final.