CLEVELAND – Amanda Serrano continues to prove why she is one of the best combat sports athletes in the world. Serrano (41-1-1), who competes in MMA and boxing, stepped into the ring on Sunday against Yamileth Mercado to defend her unified WBC, IBO, and WBO titles, and needed all 10 rounds to get the job done. The bout served as the co-main event of Paul vs. Woodley , which aired on Showtime pay-per-view on Sunday evening.