Usain Bolt set his sights on breaking his 200 metres world record at the Rio Olympics after retaining his 100m crown.

The Jamaican became the first man to win the Olympic 100m title for a third time and was optimistic of going seriously quick in his favoured event.

The 29-year-old begins his bid for an eighth Olympic gold in the heats on Tuesday, with the semi-finals the following day and the final on Thursday.

And Bolt, who blamed his slow winning time in the 100m of 9.81 seconds on the tight turnaround between semis and final, said the day's rest in the 200m gave him hope of breaking his seven-year-old world record of 19.19secs.

"This is one of the biggest things," said the world's fastest man, whose confidence is flying after he all but jogged to 9.86s in the 100m semis.

"I really want (the) 200m world record. If I can get a good rest after the semi-finals, there's a possibility I could.

"When it comes to the 200m I'm much more confident. The 100m is always the hardest one for me."

So good did Bolt feel in the 100m semis in fact that he claimed, had he ran it flat out, he could have threatened his world record of 9.58.

"I felt really smooth, I knew if I ran through the line I probably would have ran the world record or close to it," said Bolt, who took gold ahead of Justin Gatlin and will go head-to-head with the two-time drug cheat over 200m as well.

It was some statement from a man who has not run under 9.77 since he won gold at London 2012 in 9.63 and a sign that he knows he is in form.

Bolt accused Gatlin of disrespect in the run-up to the Games after the American questioned his decision to pull out of the Jamaican trials with a hamstring strain.

But Gatlin, the sport's pantomime villain who was loudly booed by the crowd inside the Olympic Stadium, was full of praise for him on Sunday night.

"I have the utmost respect for Usain," the 34-year-old said. "When he comes away from the track he's a great guy, a cool guy. There is no rivalry between us, no bad blood.

"He has pushed me to be the athlete I am today. I hope that he can say the same for me. When it comes down to it I've given him the closest races in all his career. To be able to say that at the age I'm at right now is a true honour."

Despite his victory on Sunday, Bolt suffered the rare - perhaps unique in his career so far - experience of being upstaged on the track by South African Wayde van Niekerk's 400m world record of 43.03.

Van Niekerk trained with Bolt in Jamaica ahead of the Games.

Bolt said: "My coach (Glen Mills) said he's the only guy right now, apart from me, that can break the 400m world record. He's got speed and strength. I'm very happy for him."

A match-up between the two over 400m will not happen - Bolt has consistently maintained that he will not step up to the one-lap event, despite Mills' desire for him to do so - but he is keen on a showdown over 300m, possibly next year.

"That would be a good race. I'd really like to compete against him over 300m," said Bolt.

Before that, though, he has the small matter of the 'triple triple' of Olympic sprint crowns to achieve.

Another gold in the 200m would leave him just a 4x100m relay success away from his goal. Few, if any, would bet against him.