Hori was then pitted against fellow Japanese prospect Tatsufumi Tomihara in the quarterfinals of the K-1 Survival 2003 Japan Grand Prix.

He won via decision, and moved on to face Musashi, the premiere heavyweight Japanese star at the time.

The bout was Mo's K-1 debut, and after the judges declared the fight would go to the overtime fourth round, he defeated Hori with a knockout.

Hori then fought Cyril Abidi in a valiant effort, losing via TKO with just two seconds left in the fight.

After winning the quarterfinal match, Hori fought Nobu Hayashi, a 24-fight veteran at the time.