Roman Greenberg successfully defended his IBO Intercontinental heavyweight title late Saturday night, knocking out Russian journeyman Alexei Varakin in the sixth round of the bout in Monte Carlo, Monaco. Greenberg, who remained unbeaten with a 23-0 record in his career, was anything but convincing on Saturday, struggling to contain the 31-year-old Russian for large parts of the fight. The 24-year-old Israeli survived thanks to an awesome right uppercut he delivered midway through the sixth round and from which the Russian could not recover. "If I didn't believe that I could be the world champion, I wouldn't be fighting," Greenberg told The Jerusalem Post before the fight against Varakin. "If everything goes as planned, I will win my next two fights in November and December and next year I will fight for a world title." Despite being unimpressive, Greenberg got through the first of his remaining fights this year and another win on December 9 in the US will keep him on course for a future fight for a world heavyweight championship. Mayweather defeats Baldomir Floyd Mayweather Jr. dominated nearly every minute of every round Saturday night to earn a lopsided decision over Argentina's Carlos Baldomir for the WBC welterweight title. Mayweather remains unbeaten with the win and sets up a possible megafight next year against Oscar De La Hoya. Baldomir never went down and never appeared in trouble, but his face was bloodied from the first round on and he took punch after punch to the face from the much quicker and much more skilled Mayweather. Two judges gave Mayweather every round, while a third gave him all but two rounds. Mayweather remained unbeaten in his 37th professional fight, and looked good enough to set up a possible fight with De La Hoya in May that could be one of boxing's richest ever. "I fought a perfect fight," Mayweather said. AP contributed to this report.