Jakob Ingebrigtsen finished behind Cole Hocker in the 1500m final, with Hocker setting a new Olympic record of 3mins 27.65secs.
What happened?
Ingebrigtsen went out at world record pace, passing the 400m mark in 54.9 seconds.
He knew this was a "dangerous" place to be, but it was too late.
Ingebrigtsen failed to build a gap to his rivals, including Josh Kerr and Cole Hocker.
He was vulnerable after the two previous major championship finals.
Why it matters for Jakob Ingebrigtsen
Ingebrigtsen's strategy has rarely varied, with a slow wind-up usually disposing of his rivals.
But this time, he went out too hard, opening with a 54-second lap.
He said "I opened with a 54-second lap, that wasn’t the plan at all."
Ingebrigtsen felt strong, but didn't realize the pace he was on.
What comes next?
Ingebrigtsen will need to reassess his strategy for future races.
He has been the dominant force in the 1500m since the Rio de Janeiro 2016 final.
But now, he faces stiff competition from rivals like Josh Kerr and Cole Hocker.
Ingebrigtsen's era may be coming to an end, with new challengers emerging.
Ingebrigtsen's European record of 3mins 26.73secs, set last month, proved misleading.
He was on pace for the world record, but it was not to be.
Ingebrigtsen's fittest year yet, but largely the same version, was not enough.
He finished behind Hocker, who ran a stunning final 400m in 53.35 seconds.
The 1500m final was a thrilling race, with Ingebrigtsen and Hocker battling it out.
But in the end, Hocker's tactics paid off, and he took the gold.
Ingebrigtsen will need to regroup and come back stronger in his next race.
The question is, can he adapt and overcome his rivals to regain his dominance in the 1500m?