By Edward Chaykovsky

In his last fight against Manny Pacquiao on May 2nd, WBC/WBA welterweight champion Floyd "Money" Mayweather generated 4.4 million pay-per-view purchases.

His upcoming fight against Andre Berto, on September 12th at the MGM Grand in Las Vegas, is expected to do much less. Some insiders are doubting whether the fight can break a million buys, especially with a little more than a month away from the event take place.

Some of the oddsmakers and betting sites have Berto as high as a 80-1 underdog in the fight. Berto has gone 3-3 in his last six and stopped Josesito Lopez in six rounds back in March.

A victory for Mayweather would match the record of the late heavyweight champion Rocky Marciano, who retired in April 1956 with an unblemished record of 49-0.

Stephen Espinoza, Executive Vice President and General Manager for Showtime Sports, confirms the upcoming fight is the last on Mayweather's six fight exclusive agreement with his network.

Mayweather says the September fight will be the final ring outing of his pro career.

“When Showtime Networks and Floyd Mayweather teamed up for the first time in 2013, it was called a record-breaking deal – and that’s exactly what it has been,” said Espinoza. “Through five fights of the six-fight term, the results have exceeded our grandest expectations."

Many fans are not pleased with the selection of Berto and expressed their displeasure on the social networks. Espinoza is not worried about the negative reaction. He expects Berto to make things interesting when he steps in the ring.

"Floyd has never hesitated to take on the best of the best in his division.  In Andre Berto, Floyd has chosen an opponent who always comes to fight and always entertains.  Berto’s power and athleticism make him a legitimate threat against any opponent, and against Floyd, we expect Berto to be as aggressive as ever," Espinoza said.