Welterweight champion Floyd Mayweather, arguably the best pound-for-pound boxer of his era, has stated that his Sept. 12 bout with Andre Berto at the MGM Grand in Las Vegas will be the last fight of his career. After a monumental victory over superstar Manny Pacquiao in May, Mayweather will be seeking to retire with a perfect 49-0 record, like heavyweight great Rocky Marciano. With Mayweather's legacy on the line, Berto has a tough task ahead of him.

Berto (30-3, 23 KOs) immediately entered the welterweight fight as a major underdog, and is currently listed at +1200 by online betting side Bovada.lv. Ring Magazine doesn't even list the Florida native as a top 10 welterweight, likely due to Berto's lack of wins against elite opponents. Most boxing experts were a bit surprised that Mayweather would choose an opponent with limited name recognition. 

But the 31-year-old has won his last two fights, and has victories over respected veterans Josesito Lopez, Luis Collazo and Steve Forbes. It's in his performances in losses that Berto has gained respect in the boxing community. Berto was stunned by a first-round knockdown against Victor Ortiz in 2011, but valiantly fought back to go 12 rounds in an action-filled fight. But his brutal bout with Roberto Guerrero truly elevated Berto's stock. While he lost on all three scorecards, many regarded the slugfest with Guerrero as the best fight of 2012.

Unlike Ortiz and Guerrero, a defensive specialist like Mayweather will be reluctant to have heated toe-to-toe exchanges. Mayweather is among the most intelligent boxers in boxing history, and knows how to avoid letting his opponent pace the fight.

But Berto has a chance to achieve an upset victory if he can stick to a smart game plan and take the right chances. While the odds are stacked against Berto, Mayweather may be overconfident after his lucrative victory over Pacquiao.

Here are three ways Berto can shock the world and defeat Mayweather in a fight that is expected to come down to the scorecards.

Pick Rounds To Be Aggressive

Berto must avoid letting Mayweather dictate the urgency of rounds. To avoid a desperate push in the late rounds, Berto should look to make Mayweather chase him in the opening rounds, and perhaps get the 38-year-old Mayweather tired and frustrated by the later rounds. If Berto can keep jabbing and moving, while avoiding Mayweather's power punches in the opening rounds, he may force Mayweather to take more risks. Berto would need to avoid fatigue problems, and if he's fit, he could find just enough openings for power punches late in the fight.

Don't Fall For The Should Roll, Maintain Composure

Mayweather uses the defensive tactic to frustrate his opponents, and is clever enough to bait Berto into thinking he has an opening for a power punch. Berto needs to avoid such false hopes, and stick to a game plan of moving around and letting Mayweather chase him. Mayweather won't use his shoulder roll unless he feels his opponent wants to go toe-to-toe, and Berto should mostly avoid that since Mayweather has a three-inch reach advantage. Despite his defensive skills, Mayweather is capable of being hit. For Berto, it's a matter of hoping Mayweather opens himself up.

Mayweather thrives off his opponents' mistakes, so Berto needs to keep calm and fight a tactical bout. Berto would be best served to keep his feet moving around the ring, and be judicious with his power punches. 

Throw Lots Of Punches In The Middle Rounds

Should Berto stay active and defensive in the opening rounds, Mayweather may have no choice but to be more assertive out of fear that the judges awarded Berto some early rounds. In fact, after his rather lackluster exchanges with Pacquiao, it wouldn't be surprising for Mayweather to consider going out like a hard-hitter and seek a knockout after so many "boring" fights. Should that be the case, Berto can surprise Mayweather with flurries in the middle rounds. Though Mayweather often wins power-punch exchanges, Berto has the chin and the enough strength in his power punches to perhaps come out on top and perhaps land clean shots. Berto should take a page out of Marcos Maidana's aggressive strategy in 2014. A mixture of overhand rights and some fierce uppercuts might be enough to win important middle rounds and get under Mayweather's skin for the final rounds.