Usain Bolt raced for the first at the 2016 Olympics and won his opening round 100m heat in 10.07 seconds.
Bolt, seeking an third consecutive Olympic title in the blue riband event, clocked 10.07 seconds at the Olympic Stadium.
"Now I got the jitters out of the way, I'm ready to keep moving forward", Bromell said to Lewis Johnson. "It wasn't the best start". The semi-finals and final take place tomorrow evening with the final at 5.25am on Monday.
Phelps was beaten in his last Olympic individual race Friday night by a 21-year-old who grew up idolizing him.
Usain Bolt at the start of today's qualifying round.
On the track, though, he means business.
The superstar qualified in a leisurely 10.07 seconds, picking up the pace after lumbering from the blocks and looking stiff in his warm-up. Just raised arms and another clap.
"It' s like a soccer crowd in here", Gatlin said.
"As you become a more seasoned athlete you understand the importance of running at the Olympics".
His time of 10.07 seconds trailed that of his longtime rival Justin Gatlin by.06 seconds, but Bolt was running into a headwind while the American had the wind on his side.
But James Ellington crashed out thanks to a time of 10.29.
Antigua and Barbuda sprinters, Daniel Bailey and Cejhae Greene, are through to the 100 metres semi-finals at the Olympic Games in Rio de Janeiro.