Usain Bolt declared himself "the greatest athlete" to have lived after sealing an Olympic sprint double.
"I'm a living legend," he said, after becoming the first man to successfully defend both 100m and 200m titles.
"Usain Bolt always said he wanted to be a legend, and in order to do that he had to do the double double. I guess the legend continues.
"He's still quite easily the best and he could be for as long as he wants. I suspect he is going to lack a little bit of motivation, because he likes doing the other things. In the last few years our sport would have sunk without a trace without him. We all owe him a debt of gratitude because he's bringing the people in."
Before Thursday's 200m final
the Jamaican had suggested he could break his own world record of 19.19 seconds.
Afterwards, he admitted: "I was fast but I wasn't fit enough," before sounding an ominous warning: "I am not ready to retire. I love this sport."
Jamaica completed a clean sweep in the 200m, with Yohan Blake winning silver and Warren Weir bronze behind Bolt's 19.32 seconds.
"We pushed each other and we're happy," Bolt said after the race.
Although he broke neither the World or Olympic records on this occasion, Bolt was full of joy and bravado in the post-sprint media conference, insisting he had left a permanent imprint on the sport.
"I'm now a living legend," Bolt added. "Now I am going to sit back, relax and think about what's next.
"Bolt, as ever, celebrated his fifth Olympic gold like a glorious loon - crossing the line with an admonishing finger to his lips, throwing himself down into 10 press-ups, seizing a photographer's camera to snap back at the flashes fired at him from all around."
"I don't know what I really want to do after this, whether to run the 100 or 200 or try something else. I need to find a goal that's going to motivate me to great things. The rest of the season I am just going to have fun because I did what I came here to do."
Bolt led his compatriot Blake, 22, from the starting blocks but slowed as he neared the finish line.
"I came off the corner, I could feel the strain on my back a little bit, so I was trying to keep my form," he said. "But I stopped running because I knew it wasn't going to be a world record.
"I really wanted to do it in the 200m, but I'm happy. I came here and I gave it my all and I'm proud of myself."
Usain Bolt retains 200m title to make Olympic history