Floyd Mayweather Jr.
Jul 14, 2014; New York, NY, USA; Floyd Mayweather Jr. reacts during press conference at Times Square. Reuters

Floyd Mayweather Jr. has been the gold-standard of boxing for almost two decades. His high-profile clashes against Oscar De La Hoya in 2007 and Canelo Alvarez in 2013 were surefire blockbusters, breaking all sorts of pay-per-view and gates records. With an undefeated record and huge fanbase, Mayweather is no doubt on top of the boxing world.

But there were times when his reputations were put to question. He might have boasted victories against elite competitions, but he never faced some who are considered real threat to his throne during their prime.

Mayweather claimed he's the best ever. However, he could have silenced his critics if he only accepted challenges from these top-5 fighters.

Winky Wright of 2004

Ronald Lamont Wright was at the peak of his career in 2004, having defeated convincingly Sugar Shane Mosley twice in that year. He might not have a killer punch, he used his length, agility and boxing savvy to dominate his opponent. According to ESPN boxing analyst Brian Campbell, Wright at light middleweight could have been a handful for Mayweather, if the fight happened in 2004.

Wright's technical skills would easily neutralize Mayweather's defence, making this showdown a must-see. However, this fight never happened for the reason that Money May only jumped to light middleweight division in a fight against De La Hoya.

Sugar Shane Mosley of 2003

Fighting Mosley at his prime could have been a much tougher opponent for Mayweather, because the Pomona, California native possessed the speed in both feet and hands along with the power to overwhelm him.

In 2010, Mosley nearly buckled down Mayweather with two thunderous right hand shots but failed to sustain the momentum in the early rounds. If only Mosley had the stamina and the power he had in 2004, the outcome of the fight would have been different. There were negotiations in 2002 about a possible showdown between the two, but contract disputes delayed the fight.

Antonio Margarito of 2005

The Tijuana, California fighter would have been a better version of Marcos Maidana to Mayweather if their fight took place in 2005. With his length and rugged style of boxing, Margarito will provide all sorts of trouble to Money May's shoulder roll defence. Moreover, El Tornado had the power to sneak in an upset win against quality opponent on any given day.

Paul Williams of 2007

Williams was an unstoppable force in the welterweight and super-welterweight division during his prime. At 6-foot-2, Williams could have really pushed Mayweather to the limit at the time where he TKOd most of his opponents. He was a freak of nature with powerful punch - someone Mayweather never intended to fight against.

Manny Pacquiao of 2009

The Pacman was a tornado sweeping across the boxing world during that time. 2009 was an epic year for the Filipino icon, as he knocked out Ricky Hatton and Miguel Cotto in emphatic fashions. Campbell picked Pacquiao as the fighter who could have ended Mayweather's flawless record with his rare combination of power, agility and superb athleticism.

"The 2009 version of Manny would have been his toughest opponent of the group because of the speed/power combo, along with how dynamic Manny was at the time throwing punches from angles you couldn't necessarily prepare for," Campbell stated on ESPN chat session.

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