By Gregory Stangrit, photos by Viktor Sokolov

During the recent open training session in Moscow, Russia, former five division world champion Floyd Mayweather Jr. (49-0, 26KOs) wore a t-shirt which displayed the number "48."

Local reporters asked Mayweather to explain why he decided to wear that shirt, since he retired undefeated at 49-0 in September.  

Mayweather says his 48th victory, which came on May 2nd against Manny Pacquiao, was the most important victory of his professional career.

The two fighters finally came together in the ring after five years of failed negotiations. Their encounter shattered numerous financial records and generated 4.6 million purchases on pay-per-view - which blew away the existing record of 2.4 million from the 2007 PPV between Mayweather and Oscar De La Hoya.

During the majority of those five years when the fight was being discussed, a lot of critics claimed Mayweather was avoiding the contest.  

"This [shirt] is in honor of my 48th victory, which is the most important of my career. A lot of people said that I avoided this fight. A lot of people said that I couldn't win the fight. But I proved all of that was wrong, and therefore the fight against Manny Pacquiao is the most important for me," Mayweather said. 

Gregory Stangrit covers boxing for