100m sprint
[WATCH] Meet SA's new 100m Youth Champion Luke Davids
South Africa's Luke Davids won the 100m gold medal at the Youth Olympics in Buenos Aires.
Makwala, among the favorites for the 400m, would normally be scratched from the final after pulling out of another event.
Ahead of his final appearance at a major competition, Usain Bolt has tipped SA's Wayde van Niekerk to be the next track and field superstar.
Gatlin, 35, claimed the victory in 9.95 seconds in his best performance of an injury-plagued season.
Olympic champion Usain Bolt's coach believes the athlete is capable of increasing his speed even further.
Olympic silver medallist Yohan Blake will undergo surgery on a hamstring injury.
The Jamaican sprinter tested positive for the stimulant oxilophrine at a tournament last year.
Usain Bolt hopes to become the first man to win the 100 and 200 at two successive Olympics.
Usain Bolt scorched to the second-fastest 100m ever on Sunday.