RIO DE JANEIRO - Sporting immortality beckons for Usain Bolt after he captured his second gold medal of the Rio Olympics on Thursday night in Brazil as the lanky Jamaican sprinted to victory in the men's 200m event.

The 29-year-old had been aiming to break his own world record of 19.19 seconds (set at the 2009 World Championships in Berlin) and become the first man to break the 19sec barrier for the event but was unable to achieve his goal.

Instead, he clocked a time of 19.78sec from lane six at the Olympic Stadium under light rain to finish ahead of Canadian Andre De Grasse (20.02sec) and Christophe Lemaitre of France (20.12sec).

During a post-race interview, Bolt said: "No words can explain becoming an eight-time Olympic champion. The 200m means so much to me. I don't need to prove anything else."

"I wanted to run a faster time but my legs were feeling tired. The younger kids have stepped up. I proved that you can do this sport clean."

This was Bolt's third straight victory in the 200m at the Summer Games, dating back to Beijing 2008 (19.3sec) and London 2012 (19.32sec) and comes on the back of his win on Sunday in the 100m. It was also his third consecutive triumph in that event.

"The key thing was I won and you guys know it's all about the gold medal", added Bolt.

"I've put Jamaica on the map and that's all I can do. All I want now is a gold in the 4x100m."

Bolt is chasing a historic "triple triple" at the Rio Games as he aims to sweep the 100m, 200m and 4x100m events in three straight Games.

He will represent Jamaica in the 4x100m final on Friday night (9.35am Saturday, Singapore time).