18-0 Shooto champion Hayato Sakurai was considered the #1 ranked WW in the world when Anderson defeated him.
https://www.fightmatrix.com/histori...ated-historical-rankings/?Issue=46&Division=4
The highest Anderson has ever been ranked at WW though is #2.
https://www.fightmatrix.com/histori...ated-historical-rankings/?Issue=49&Division=4
Ummm...., no he wasn't. Silva beat Sakurai in August 2001. Immediately before this, in July 2001, Sakurai was ranked #3 at WW:
https://www.fightmatrix.com/histori...ated-historical-rankings/?Issue=47&Division=4