Usain Bolt ran his fastest time
of the season to win his Olympic 200m semi-final in 19.78 seconds as
Justin Gatlin missed out on a place in the final.Britain's Adam Gemili reached Thursday's final (02:30 BST, Friday) as one of two fastest losers. Gatlin, banned twice for doping offences, clocked 20.13 and failed to progress along with another big name - Yohan Blake.
The Jamaican, who won silver behind Bolt in London four years ago, has been hampered by injury over the past couple of years and faded to finish sixth in 20.37 seconds.
World number one LaShawn Merritt, who has run 19.74 this year, is likely to pose the biggest challenge to Bolt in the final.
But Bolt believes he can break his world record of 19.19 and could even go under 19 seconds in the final.
"I definitely think I can try for the world record, I definitely feel that," he said. "I need to run efficiently and get into the straight and run the perfect race."