LAS VEGAS: Two-time Olympic gold medalist Guillermo Rigondeaux defeated Moises Flores with a controversial fight-ending punch at the close of the first round Saturday to retain his WBA junior featherweight title in Las Vegas. The victory was controversial as television replays showed Rigondeaux landed a left hand after the round-ending bell had rang. He also landed three punches while holding Flores’ head from behind just before the knockout. The fight was on the undercard of the Sergey Kovalev-Andre Ward world title light heavyweight bout at the Mandalay Bay hotel and casino. Rigondeaux improved to 18-0 with 12 knockouts, while Flores, of Mexico, dropped to 25-1, with 17 KOs. The Cuban-born Rigondeaux was announced the winner, but after the fight Nevada Athletic Commission executive director Bob Bennett told broadcaster HBO that they might have to review the decision. “We will take a look at it. If the punch landed after the bell it is a disqualification,” Bennett said. “We want the right fighter to win. Anything is possible. We could take a look at it and do the right thing.” Flores stayed down for several minutes and had to be helped back to his corner where he sat during a lengthy review that eventually resulted in Rigondeaux being crowned the winner.