Speculation continues to build about a potential mega-fight between Floyd Mayweather and Manny Pacquiao in 2015. As the New Year begins, the two stars have separated themselves as the best welterweights in all of boxing.  

Mayweather ranks as the clear No.1 athlete in the sport, regardless of weight class. Even at 37 years old, the boxer remains undefeated and has yet to face an opponent that’s been able to legitimately challenge his undefeated record.

In his two fights in 2014, Mayweather took on Marcos Maidana. Maidana put up a much better fight than many had expected when the two boxers met in May, but Mayweather still walked away with a majority decision. Four months later, the rematch wasn’t even close, and all three judges scored the bout for the best fighter in the sport.

Mayweather and Canelo Alvarez had the highest-grossing fight of all time when they fought in Sept. 2013. It was thought that Alvarez might be one of the few boxers that could give Mayweather some trouble, but the undefeated boxer won with ease.

Two years ago, it appeared that Pacquiao might no longer be the second-best welterweight in boxing. His two losses, though one highly controversial, seemed to be a possible indication indication that PacMan was no longer among the elite fighters in the sport.

Since Nov. 2013, Pacquiao has proven that his losses to Timothy Bradley and Juan Manuel Marquez were nothing more than a blip on the radar. After an easy win over Brandon Rios, Pacquiao reclaimed his WBO welterweight title with a unanimous victory in his rematch with Bradley. Just a few weeks before the end of 2014, Pacquiao had an utterly dominant win over Chris Algieri, knocking down his opponent six times and seemingly winning every round.

With both Mayweather and Pacquiao looking for an opponent in their next fight, it only makes sense that they should fight each other. They are the top fighters in their division, and would be clear favorites over anyone else.

Juan Manuel Marquez knocked out Pacquiao in Dec. 2012 and won his last fight against Mike Alvarado. However, he was beaten by Bradley in Oct. 2013, whom Pacquiao should’ve be named the winner over twice. Pacquiao also beat Marquez twice before suffering the 2012 loss to his rival.

Bradley might be the third-best boxer in the division, but he’s failed to win his last two fights, losing to Pacquiao and fighting to a controversial draw with Diego Chaves a few weeks ago.

Amir Khan has proven himself to be in the class just below Mayweather and Pacquiao, winning four fights in a row, including unanimous decisions over Luis Collazo and Devon Alexander in 2014. He could get the opportunity to catapult himself among the elite fighters in the division, if Mayweather and Pacquiao don’t end up meeting in the ring. Khan has been rumored has a possible opponent for both boxers.

Maidana, Keith Thurman and Shawn Porter also rank among the best welterweights not named Mayweather or Pacquiao.