Keith Thurman defeated Luis Collazo in his last bout to extend his undefeated record to 26-0. "One Time" is now the No. 4 ranked Welterweight fighter in the world behind only Floyd Mayweather, Manny Pacquiao and Kell Brook.

Thurman is also regarded as the most powerful boxer at the 147 pound weight class. Still just 26 years old, Thurman is one of the rising young stars in the boxing world. His speed, athleticism, combo punching, and elite power punching make him one of the most feared fighters.

So, who is next for Thurman?

While boxing fans everywhere would love to see Thurman face Floyd Mayweather in his next fight, that doesn't appear very likely. Mayweather is scheduled to face Andre Berto in what should be his 49th career victory. Many think Mayweather will retire after that fight. Regardless, Mayweather has shown no interest in fighting Thurman in the future.

A more possible, but still unlikely matchup would be Thurman against Manny Pacquiao. Pacquiao is currently sidelined recovering from shoulder surgery, but Thurman recently acknowledged he was "open" to a possible bout with Pacman. This would do wonders for Thurman's career because of Pacquiao's all-time great legacy, but timing may not work out. Pacquiao's timetable has not yet been determined, and Thurman can't take such a long waited risk unless he were to fight someone else beforehand.

Another older veteran who could be a possibility is Juan Manuel Márquez. The Mexican veteran is far past his prime at the age 42, but like Thurman, he packs a powerful punch. Márquez is semi-retired, so this one would be hard to make as well. If this fight were to take place in Mexico the ratings would skyrocket.

More than likely Thurman will have to face a younger opponent in his next fight. There's a lot of younger welterweight stars today that could face Thurman next. Stars such as Timothy Bradley, Kell Brook, Amir Khan, Marcos Maidana and Danny Garcia would all make sense. Brook will fight Argentinean Diego Gabriel Chaves in October, but rumors have swirling that he and Thurman could meet in the future. Brook and Thurman are viewed as "the future of boxing" given their young age and the fact that Mayweather and Pacquiao are nearing retirement.

Bradley, like everyone else, has called for a future bout with Mayweather several times but hasn't got anywhere on that process. Bradley is a similar fighter to Mayweather in the fact that he lacks power, but has superior speed and escapability. Bradley only has one loss in his entire career, which came against Pacquiao last year via decision.

A Thurman-Garcia showdown would be very interesting. Garcia is new to the welterweight division after knocking out Paulie Malignaggi recently. Garcia knows facing Thurman would bring in high numbers, but Thurman is more interested in facing Khan.

"Personally, I'm highly interested in an Amir Khan fight. A lot of fans are interested in it. We both fought Luis Collazo and Julio Diaz so we have two common opponents" Thurman said.

Khan has won his last five bouts after his 2012 loss to Garcia. Khan is an average fighter, but many feel as if he is somewhat overrated because he has yet to beat a top contender.

 Follow Damon Salvadore on Twitter @DamonSalvadore1