Janaican Usain Bolt stumbled and then recovered to win his semifinal heat in 9.96 seconds, reaching the world championship final in a performance that cast doubt over his ability to beat Justin Gatlin in the final later Sunday.
American Gatlin qualified fastest in 9.77.
Jamaican Asafa Powell also secured his spot in the semi-finals after putting in a strong run to finish second behind Tyson Gay in his semi-final. Gay clocked 9.96 for top spot while Powell was just behind 9.97.
"Easy. Breezy," Gatlin said before going to warm down. The final was scheduled for 8:15 am Jamaica time (9:15 pm local time)
Gatlin, who won the 100 at the 2004 Olympics before serving a four-year suspension for doping, is unbeaten in 2015 and had the season-leading time of 9.74 heading into the championships. The 33-year-old American took bronze behind Bolt at the 2012 Olympics and silver at the 2013 world championships in Moscow.
The only time Bolt has failed to win gold in a sprint at a major championship since the 2008 Olympics was when he was disqualified for a false start in the heats of the 2011 world championships.