Floyd Mayweather has confirmed what the entire boxing world has known for weeks -- he’ll be fighting Andre Berto on Sept. 12 in Las Vegas. After fighting Manny Pacquiao in the highest grossing pay-per-view of all time, the undefeated boxer will take on an underwhelming opponent in what could be the final bout of his career.

Berto is not among the top fighters in the division, and fans will have to pay to watch the bout on Showtime PPV, instead of seeing it for free on CBS as had been speculated. Considering the 31-year-old has lost three of his last six fights and has never defeated an elite opponent, Berto is an extremely heavy underdog.

Berto has been given worse odds than any of Mayweather’s recent opponents, and a win for him would be one of the biggest upsets in boxing history. He’s a +1600 underdog at Bovada.lv, while Mayweather is considered a virtual guarantee to win with -10000 betting odds.

Pacquiao is the best fighter that Mayweather has ever been in the ring with, so he was only a +200 underdog just hours before their mega-bout. But other opponents were given a much better chance to defeat Mayweather. Mayweather was a -800 favorite leading up to his rematch with Marcos Maidana a year ago, and he was given -1000 odds to win their first fight in May of last year. Mayweather was a -280 favorite against Canelo Alvarez in Sept. 2013, and he had -750 odds to defeat Robert Guerrero four months earlier.

Two of Berto’s last three losses have come against opponents that Mayweather has beaten with ease. Berto lost to Guerrero in a unanimous decision a little less than three years ago, and he suffered the same fate against Victor Ortiz in April 2011. Ortiz suffered a fourth-round knockout to Mayweather, against whom he was a +500 underdog.

Berto is coming off two straight wins, and he hasn’t lost in two years. But his victories over Josesito Lopez and the unknown Steve Upsher Chambers don’t inspire much confidence that he can give Mayweather much of a challenge. Berto’s last loss came at the hands of Jesus Soto Karass, who has 10 losses in his career.

Much of the sports world was disappointed in Mayweather’s fight with Pacquiao, and Berto’s aggressive style could allow for a much more entertaining bout. Only nine of his 34 fights have not resulted in a knockout, but it’s more than likely that Mayweather’s defensive prowess will result in another fight with limited action.

None of Mayweather’s recent opponents have connected with more than 26 percent of their attempted punches, and Sept. 12 should be more of the same. Even though Mayweather doesn’t allow other boxers to inflict much damage upon him, he doesn’t end fights early, going the distance in eight of his last nine bouts.

Prediction: Mayweather by unanimous decision