Joshua Van shocked fans by defeating Brandon Royval on moment's notice ... and he's wasting no time looking at his next potential opponent -- telling TMZ Sports he'll fight Alexandre Pantoja "without respect," 'cause he's ready to be the champ!!
Van pulled off an upset win over Royval at UFC 317 ... which was two weeks after a TKO victory against Bruno Gustavo da Silva.
Pantoja, who fought on the same card, called out Van after handling his matchup with Kai Kara-France .