Former pound-for-pound king Manny Pacquiao suffered a setback in his preparation for his showdown with Brandon 'Bam Bam' Rios after sustaining a slight ankle injury while playing hoops last weekend.

Pacquiao has already started doing light conditioning drills for the Rios fight, one of which is playing basketball. Playing basketball has been part of Pacquiao's preparation for his previous fights, but that proved to be costly for him weeks before the arrival of Freddie Roach.

The fighting congressman believes the ankle sprain was caused by the absence of ankle support.

"I forgot to wear ankle support," Pacquiao told ABS-CBN sports writer Dyan Castillejo.

Roach is expected to arrive in General Santos City to officially begin Pacquiao's training camp. Pacquiao is coming off a knockout loss to rival Juan Manuel Marquez in December, making his upcoming bout with Rios a must-win for his boxing career.

Meanwhile, Rios is reportedly at the peak of his training months before his rumble with the eight-division world champion. Rios, who's also coming off a loss to Mike Alvarado earlier this year, considers the Pac-Man fight the biggest of his career.