American boxer Floyd Mayweather Jr says he is ready to come out of retirement for a third time. The undefeated five-division world champion, who has not fought for 17 months, will take on Mexico's five-times world champion Juan Manuel Marquez in a non-title welterweight bout in Las Vegas on July 18. The 32-year-old praised his opponent and said he wanted his comeback fight to be against one of the sport's best. "Marquez is a hell of a guy," Mayweather Jr said. "They say to be the best you have to beat the best. So we two are the best fighters in the sport right now, so when I come back I don't want to fight a has been. I want to fight one of the best in the sport. Marquez is one of the best in the sport." Mayweather, who has a career record of 39-0 with 25 knockouts, never expected to miss boxing as much as he did after announcing his retirement last June. "I was really missing just being around the sport," said the American, who is known for his blistering hand speed and superb defence. Mayweather has not fought since his tenth round stoppage of Britain's Ricky Hatton in a WBC welterweight title bout in December 2007, but believes he is already in good shape. He said: "I was training every day, going to the fitness gym and to the boxing gym every now and then and working on it anyway, so I said to myself I may as well take it to the next level. Go back to the ring and box have some fun and put some x's on my mark in history."