Rank-and-file wrestler Aoiyama moved into the outright lead Thursday at the Spring Grand Sumo Tournament after Hakuho suffered an upset loss to sekiwake Shodai.
The big Bulgarian continued his impressive run by beating Mitakeumi and improving to 11-1, while Hakuho went down for just the second time in 11 bouts against Shodai at Edion Arena Osaka.
Hakuho (10-2) delivered a powerful right-hand slap before driving Shodai to the edge, but the sekiwake powered his way back to grab a belt hold and force out the yokozuna, who took his first loss of the meet two days earlier.