LAS VEGAS, Aug. 23 -- Seven months after Shakur Stevenson stopped the clock on his WBO lightweight title reign, Teofimo Lopez walked out of T-Mobile Arena on Saturday night as a three-division world champion, having added the WBA welterweight belt to a collection that already crossed two weight classes.

The winning margin was narrower than Lopez would have preferred. One judge could not separate them, scoring it 114-114. The two who did give Lopez the edge, by 115-113 and 116-112, produced the majority decision that made the victory official and the moment real. Rolly Romero, who came into the night as the defending champion and left without a belt, described the result as a robbery before the ring had cleared.

What CompuBox measured to...