By Mark Lamport-Stokes LAS VEGAS (Reuters) - Floyd Mayweather Jr. signed off from professional boxing as he had planned on Saturday, going out unbeaten and on his own terms as 'The Best Ever' after improving his career record to 49-0. After a stellar 19-year run that produced world titles in five weight divisions and earnings in excess of $800 million, Mayweather bade farewell to the ring with a clinical display to earn a unanimous decision over fellow American Andre Berto. "I had a game plan from the very beginning," Mayweather, 38, said of his career during a lengthy news conference after retaining his WBC and WBA welterweight titles in the MGM Grand Garden Arena. "I always knew what I wanted to do -- be outspoken, be one of a kind. To be in the sport for 19 years and to be world champion 18 years, I've had a remarkable career. "If you put them (opponents) in front of me, we see what they can do. It's all about that IQ. I'm 10 steps ahead of any fighter. I take whatever is your best attribute and take that away from you, make you do what you don't want to do." Mayweather, who matched the 49-0 career record set by former heavyweight champion Rocky Marciano, is widely regarded as one of the best defensive practitioners of all time while his ability to out-think opponents and adjust strategy midway through fights is unparalleled among contemporary fighters. However, he has also been a polarising figure because of his arrogance and flamboyant showmanship, and has certainly not always endeared himself to boxing fans with his repeated claims that he is TBE (The Best Ever). "It's crazy," smiled Mayweather, whose defensive brilliance and agile movement helped him avoid punishment from opponents throughout his career. "I've been in the sport of boxing my whole life and they say I'm wrong for saying I'm the best. "Every champion -- (Muhammad) Ali, Sugar Ray Robinson, Sugar Ray Leonard, Larry Holmes -- the list goes on and on. They opened up the doors and paved the way for where I am today and I'm appreciative. "But now the young fighters say, 'We want to be like Mayweather.' It's not cool to take punishment in the ring. I'm not perfect but I strived to be a perfectionist." Asked whether he might 'get that itch' to come back for another bout, as he did in late 2009 when he returned from a 21-month 'retirement', Mayweather replied: "My career is over. It's official. My 49-0 record is part of boxing. "I'm financially secure and I'm in good health. I'm looking forward to finding the next Floyd Mayweather and seeing someone break all these records I set. Records are meant to be broken. "I am leaving the sport with all my faculties, I'm still sharp and smart. I've accomplished everything in this sport, there's nothing else to accomplish." (Editing by Sudipto Ganguly)