Updated

Floyd Mayweather Jr. has agreed to fight Saul "Canelo" Alvarez on Sept. 14 at the MGM Grand in Las Vegas.

"I'm giving the fans what they want," Mayweather said in a message via Twitter.

Mayweather fought May 4 and remained unbeaten with a unanimous decision over Robert Guerrero to retain his WBC welterweight belt. The 36-year-old Mayweather (44-0, 26 KOs) will take on a fighter who is the WBC and WBA light middleweight title holder.

Alvarez (42-0-1, 30 KOs) scored a 12-round unanimous decision over Austin Trout on April 20 to unify the belts.