The student became the master in the men's 3000m steeplechase as Conseslus Kipruto set a new Olympic record to dethrone Kenyan compatriot Ezekiel Kemboi, who announced his retirement after the race.
Kipruto played second fiddle to the legendary Kemboi at the 2013 and 2015 World Championships, but on this occasion there was a ceremonial passing of the torch as the 21-year-old burst to victory, while after four Olympics Kemboi has opted to call it a day.
There was nothing to split Kipruto, Kemboi and United States' Evan Jager as the athletes took the bell.
Kipruto found the extra gear, though, and he was able to start celebrating his win while turning the final corner such was his dominance, a time of minutes and 3.28 seconds representing a new Olympic record.
Kemboi had to settle for third after being outpaced by Jager on the home stretch.
Mo Farah qualified from the first 5000m heat, which was won by Ethiopian Hagos Gebrhiwet, but only after a surviving a last-lap scare.
Farah stumbled after colliding with Hassan Mead but managed to stay on his feet and the 33-year-old - unbeaten at major events in the 5000m and 10,000m since 2011 - retains hope of an Olympic "double-double".
In the women's 800m heats, South Africa's Caster Semenya, who holds the quickest time for the distance in 2016, comfortably won her heat in one minute and 59.31 seconds to reach the semi-finals.
Semenya is aiming to go one better than the silver medal she won in London 2012 and headed to Rio on the back of eight wins from as many races in 2016.
Defending world champion Marina Arzamasova ran a season-best time to qualify, while Francine Niyonsaba - considered by many as Semenya's main rival - is also through. Canada's Melissa Bishop ran the fastest qualifying time.
Ashton Eaton is bidding to become the first decathlete since Daley Thompson in 1984 to defend his Olympic title and he leads after three events.
The American, the world record holder, was only second fastest in the 100m but he hit the front following the long jump after posting a distance of 7.94 metres, before upping his lead to 95 points with a throw of 14.73m in the shot putt.
There was a surprise in the men's hammer qualifying as world champion Pawel Fajdek of Poland failed to qualify. Compatriot Wojciech Nowicki finished on top with a throw of 77.64 metres.
On so many occasions it has been Kemboi that has mustered the extra burst in the 3000m steeplechase but, at 34, a new era has seemingly been ushered in by Kipruto's victory.
QUOTES OF THE DAY
"I've got such a long stride, I get tripped up or tangled up with someone. But I managed to stay on my feet. It was quite nerve-racking." - Farah describes his collision with Mead.
"I am not focused on any world records, I am focused on enjoying my championship and it's going to be a tough 800. Times don't matter but medals matter." - Semenya cares about medals not records in Rio.
"Sometimes you just need to make a decision and I have come to the decision that today is my last event." - Kemboi, after two Olympic and four World Championship golds, calls it a day.
Kipruto fell well short of the world record best, but his time of 8:03.28 represents a new Olympic landmark.
There is still plenty to come in the Olympic Stadium on Wednesday. Dafne Schippers goes up against Tori Bowie and Elaine Thompson in the women's 200m final, while Usain Bolt continues his bid for a 'triple-triple' over the same distance in the men's semi-finals.
American Brittney Reese also defends her long jump title, while the women's 100m hurdles final takes place and is seemingly wide open.