MANILA, Philippines — If Floyd Mayweather decides to stay retired, the man whom WBA welterweight champion Sen. Manny Pacquiao could fight next is undefeated Keith Thurman whose nickname “One Time” is supposed to herald his one-punch knockout power.

Thurman, 30, is recognized by the WBA as its welterweight champion in the “super” category while Pacquiao, 40, is the WBA titlist in the same division but in the “regular” class. A unification title fight to decide who deserves the WBA welterweight belt on an exclusive basis makes sense particularly as the governing body has been criticized for commercializing the sport by declaring champions in several categories to maximize earning from sanction fees. At the moment, the WBA has 11 “super,” 16 “regular,” two “gold” and three “interim” champions in 17 weight divisions.                                                                                    

The other day, Thurman called out Pacquiao to determine the “real” WBA ruler while on vacation with his Nepalese wife Priyana Thapa in Tokyo. The Japanese capital is where Thurman met Priyana Thapa in 2016. She worked for her father in a bar called Vibration in the Roppongi district. Thurman, whose father is African-American and mother is of Polish-Hungarian descent, is 10 years younger than Pacquiao and appears confident of beating him.

“The welterweight division is amazing,” he once said. “A lot of talent, a lot of fighters. I always say the welterweight division is the biggest of the small guys. It’s a very athletic division. A lot of people don’t understand the life of a fighter. Boxing is one of the hardest sports in the world. You need strength, conditioning, stamina, reflexes. In most sports, no one is punching you. You have to move backward, forward, side-to-side, take an attack, attack back.”

For a fighter known as a knockout puncher, Thurman hasn’t lived up to his reputation lately. Five of his last six fights went the distance and he’s coming off a hard-fought majority 12-round decision over Josesito Lopez at the Barclays Center in Brooklyn two weeks back. Thurman’s latest outing came after a 22-month layoff to recover from surgery in his right elbow and a bruised left hand. Against Lopez, Thurman started strong and scored a knockdown in the second round but faded as the fight progressed. He was nearly floored in the seventh round and lucky to survive a furious assault by Lopez.

What makes Thurman a leading candidate in the Pacquiao sweepstakes is his willingness to fight in the Philippines, something Mayweather will never agree to.  “Bring it in the ring,” said Thurman. “Maybe Brooklyn, maybe Las Vegas, wherever Pacquiao wants it. I’d fight him in the Philippines if I had to.” Pacquiao hasn’t fought in his home country since outpointing Oscar Larios in 2006. After the Larios fight, Pacquiao went on to figure in 23 bouts abroad.

Thurman started boxing when he was seven. He was initially trained as an amateur by Benjamin Getty who worked with Sugar Ray Leonard early in his career. Now, his trainer is Dan Birmingham. As an amateur, Thurman posted 76 KOs in 101 wins. As a pro, he’s never lost and suffered only one knockdown, a first round drop before stopping Quandray Robertson in Los Angeles in 2010. Robertson was decked in the first, second and third rounds before it was over. Thurman turned pro in 2007 and has a record of 29-0, with 22 KOs and one No-Contest. When Thurman made his pro debut, Pacquiao was already a two-division world champion and on the way to becoming the only fighter ever to capture eight world titles in eight weight classes.