Bolt is aiming to end his Olympic career with a third straight triumph in the 100m, 200m and 4x100m relay
Usain Bolt took the first strides in his bid to sweep the Olympic sprint medals for a third time on the Rio Games super Saturday as swimming legend Michael Phelps targeted a final gold to end his glittering career.
Bolt and American arch-rival Justin Gatlin glided through their preliminary races at a full and festive Rio Olympic stadium.
The 34-year-old Gatlin, the fastest man in the world this year, lead the way at 10.01sec. Bolt was slower out of the blocks but had time to see Bahrain's Andrew Fisher was in front and easily overtook to clock 10.07.
"I'm feeling good. I'm happy," said Bolt. "So now it's all about execution and getting it right when it comes to the finals."
Each has two more races before Sunday's final showdown.
Bolt is aiming to end his Olympic career with a third straight triumph in the 100m, 200m and 4x100m relay -- the so-called 'Treble-Treble'.
While the 29-year-old's superstar status is assured, Gatlin, is in Rio seeking to redeem his name after two doping bans.
Athletics, which is recovering from the Russia doping storm of the past year, is counting on both for a classic showdown.
In the track, Germany's Christoph Harting threw 68.37m in the discus to make sure the gold stayed in the family. His brother and defending champion Robert failed to qualify for the finals after straining his back flicking on a light switch with his foot.
Belgian pretender Nafi Thiam snatched a five-point lead over defending heptathlon champion Jessica Ennis-Hill after the long jump.
Thiam leaped 6.58 metres to go onto 5,018 points. British star Ennis-Hill only made 6.34m and that increased the pressure going into the final two disciplines - the javelin and 800m.
The Olympic spotlight will switch Saturday night to the final swimming battles where Phelps gets a chance to go out in glory, and a 23rd gold medal, in the 4x100 medley relay. It is an event the United States have never lost at the Olympics.
Phelps was overshadowed by Singapore outsider Joseph Schooling in Friday's 100m butterfly. The 31-year-old American was relegated to a rare three-way dead heat for silver.
Phelps called the result "kind of cool." Schooling, who was inspired to become a top-level swimmer by a meeting with Phelps as a 13-year-old, said the night had been "just crazy."
Conservative Singapore also celebrated its first Olympic gold medal ever, especially with the winner of mixed European-Asian heritage.
Schooling, 21, will receive one million Singapore dollars (743,000 US) for his gold medal as part of a programme to encourage studious Singaporeans to excel in sport.
Olympic rowing ended Saturday with Great Britain winning the men's eight gold to top the medal table for the third successive Games.
Victory was Britain's third gold on the picturesque Rodrigo de Freitas Lagoon beside Copacabana beach for a five medal haul.
New Zealand's Mahe Drysdale retained his men's single sculls' and the United States' celebrated their third straight woman's eight crown.
Australian Kimberley Brennan took gold in the women's single sculls -- Australia's first rowing gold since 2008.
In tennis, Andy Murray shrugged off a code violation for directing the word "stupid" at the umpire to crush Japan's Kei Nishikori 6-1, 6-4 and move one win away from becoming the first player to win back-to-back Olympic singles titles.
The world number two and reigning Wimbledon champion will face either 2008 Olympic winner Rafael Nadal or Juan Martin del Potro in Sunday's gold medal match.
Controversy raged in women's football after American goalkeeper Hope Solo described Sweden as "cowards" after the 2004, 2008 and 2012 women's gold medallists and reigning world champions went out 4-3 on penalties in the quarter-finals.
"We played a bunch of cowards," Solo told Sports Illustrated. "The better team did not win today."
International Olympic Committee spokesman Mark Adams called the comment "disappointing".