Usain Bolt is one step away from a remarkable 'triple-triple' after retaining his Olympic 200 metre crown with a degree of comfort on a day that saw Ashton Eaton also reaffirm his status as one of the world's most dominant athletes.
Competing in an individual event at the Olympics for the final time, Bolt surged clear of his rivals around the bend on Thursday before keeping the chasing pack at bay to triumph in 19.78 seconds, ahead of Andre De Grasse and Christophe Lemaitre.
While Bolt failed to challenge his stunning world record time of 19.19secs, he was nevertheless a clear winner and has now won the 100m and 200m at three successive Games - a staggering and unprecedented feat.
On Friday, the Jamaican will look to complete a third clean sweep of the sprint events by leading his country to victory in the men's 4x100m relay.
Eaton equalled Roman Sebrle's Olympic decathlon record of 8893 points as he held off a superb second-day charge from France's Kevin Mayer to retain the title he won at London 2012. The last back-to-back decathlon champion was the great Daley Thompson.
There were also victories for the United States in the men's and women's 400m hurdles, Kerron Clement and Dalilah Muhammad taking gold.
Another American, Ryan Crouser, produced a stunning performance to beat compatriot Joe Kovacs to the men's shot put title, while 21-year-old Sara Kolak of Croatia won the women's javelin.
The US women's 4x100m relay team overcame a scare before booking their place in Friday's final. A fumbled baton change looked to have dashed their hopes, but officials adjudged they had been impeded by Brazil, so the American quartet were given the chance to come back for a time-trial in the evening and qualified comfortably.
Even though Bolt admitted to a sense of disappointment at his time, the manner of his victory - with the rest of the field effectively out of contention after 100m - was typically impressive. The absence of athletics' ultimate performer at future Olympics will be keenly felt.
While Eaton matched Sebrle's record, Crouser was able to set a new Olympic best with a mighty winning throw of 22.52 metres in the shot put.
QUOTES OF THE DAY
"I don't need to prove anything else. What else can I do to prove to the world I am the greatest?" - Bolt knows his unmatched record speaks for itself.
"You look at 10 events - how can't there be one stinking point in there somewhere?" - Eaton jokes about his failure to claim the solitary additional point that would have seen him surpass Sebrle's score at the Athens Games in 2004.
"I felt the lactate in my legs and I thought about diving like the Bahamas runner [women's 400m champion Shaunae Miller] but I dug down deeper to get that win and my first individual gold medal," - Clement gave it everything to secure gold.
There is only one session at the Olympic Stadium on Friday, as Pontal plays host to the respective men's 50km and women's 20km race walks early in the day. The women's pole vault, men's hammer and women's 5000m finals will take place before the action concludes with the sprint relays. Can Bolt end his Olympic career with nine golds from as many finals? We shall see.