LAS VEGAS – Mikaela Mayer dug deep when she needed it most Saturday night. An active, aggressive Mayer took the fight to stubborn former WBO women’s welterweight champion Sandy Ryan at times, particularly in the 10th and final round of another terrific slugfest for Mayer’s WBO 147-pound championship. Mayer overcame Ryan’s rally in the later rounds and cut over her left eye to win their 10-round rematch by unanimous decision at Fontainebleau’s BleuLive Theater.