Sergio Pettis missed out on his chance to compete in the $1 million Bellator Bantamweight World Grand Prix, but the champion has an opportunity in front of him that could build his legacy as much as that tournament would have buoyed his bank account. Pettis, who has been out of action since a complete tear of his right anterior cruciate ligament last March, will defend his 135-pound crown Friday (9 p.m. Eastern, Showtime) at Bellator 297 in Chicago against Patricio Pitbull, the current featherweight champion and former lightweight champ who aims to become the first to win titles in three weight classes for a major MMA promotion. He’s done amazing things in this sport,” Pettis told The Post via Zoom on Tuesday. “I’ve been watching Patricio since I was, like, 16 or 17 years old, fighting for Bellator.” Much of the buildup to their fight, which serves as the co-main event ahead of a light heavyweight title tilt between champion Vadim Nemkov and longtime middleweight standout Yoel Romer...