Bolt is the defending 100m champion, winning the gold at Beijing 2008 and London 2012.
19-year-old American finished 12 seconds ahead of nearest challenger in clinching gold.
British duo fall to 6-4 6-4 defeat to India's Sania Mirza and Rohan Bopanna
Team GB beat Australia with world record time to secure second cycling gold.
The 22-year-old, who ran in a full body kit and hijab, came seventh in the preliminary race.
Spencer Wilton, Fiona Bigwood, Carl Hester and Charlotte Dujardin secure second in dressage.
Reigning champion will face Gael Monfils or Kei Nishikori for a place in the final after three-set win.
As Michael Phelps soared through the water, people wanted to know why his body was covered in marks.
The Ethiopian knocked 13 seconds off the previous mark, set by China's Wang Junxia back in 1993.
With travel problems having been conquered the Rio experience has greatly improved.
Team GB's men's four also won their fifth straight title at Lagoa Rodrigo de Freitas in Rio.
Gnabry has played just 12 minutes of Premier League football in the last two seasons.
Andy Murray is just two wins away from another Olympic medal.
Eight teams will fight against each other for gold in the men's football event.
Women's sport given equal billing at the Olympics but some coverage labelled as sexist.
Rafael Nadal takes on Thomaz Bellucci in the quarter-finals of the Olympics.
Great Britain take on Spain in a must win game on 12 August.
Usain Bolt arrives in Rio in the shape of his life and could break the world record again.
Germany and Netherlands face off in a clash of the unbeaten teams.
Athletics takes centre-stage in Rio as Team GB continue the pursuit of more medals.
Phelps created history by winning the 200m individual medley Olympic title for fourth time in a row.
India have qualified for the knock-out stages for the first time in 36 years.