Norreddine Morceli was dominant in 1500m.
7 straight years ranked number 1 in the world.
Gold in 1991. Although he ran badly in the 1992 Olympics, he did break Aouita's 7 year old world record that year.
Gold in 1993. Gold in 1995. Gold in 1996.
Then in 1997, he was in second place with less than 150m to go, chasing El Gurrouj.
Castro passed him going into the homestretch.
Morceli still had a nice lead in medal contention with 50m to go.
Then he was caught and finished 4th.
https://youtu.be/M-hpCr-7GIU?t=101
He was a DNF at the 1999 World Championships.
He finished DFL in the 2000 Olympic semis, 21 seconds back from the heat winner.
He was done at age 30.
That 1997 race looked like the symbol of his decline.