London: With a historic sprint "double-double" in the bag for Usain Bolt, Tirunesh Dibaba bids to provide another on Friday, when gold in the women's 5,000m would mean she had won both the longest track races at successive Olympics.
The Ethiopian retained her 10,000m crown a week ago with a scintillating last lap, demonstrating that she was back to her best after years of injury.
Bolt's time of 19.32 seconds in winning the 200 on Thursday night equalled the fourth fastest ever as he eased down in the last 30 metres, sensing that he was not on course to break his own world record. Silver went to his main rival and training partner Yohan Blake, and bronze to a third Jamaican, Warren Weir.
"After a rough season I came out here and did it," he said. I thought the world record was possible. I guess I was fast but not fit enough. I could feel my back strain a little bit, so all I did was to keep my form."
The successful defence of both his 100 and 200 titles was unprecedented, and confirmed him as the greatest sprinter in history.
If she can win on Friday, Dibaba will emulate the 5,000/10,000m double of Finland's Lasse Viren in 1972/76.
Her main challenger in the 5,000 may be Kenya's Vivian Cheruiyot, who has played second fiddle to Dibaba for most of her career but herself won the 5,000 and 10,000 at last year's world championships.
Bolt's triumph capped a historic day when Kenya's David Rudisha broke his own 800m world record, Britain's Nicola Adams became the first woman to win an Olympic boxing title, and the United States held off a Japanese fight back to win their third successive women's football gold.