Unlocking Potential

It all boils down to fitness for Valter Walker.

The 6-foot-6 Brazilian will look to keep his head above water in the Ultimate Fighting Championship heavyweight division when he confronts Don’Tale Mayes in a three-round UFC Fight Night 251 prelim on Saturday at the UFC Apex in Las Vegas. Walker has won 12 of his 13 bouts as a pro. He rebounded from his first career setback—a unanimous decision loss to Lukasz Brzeski—in August, when he put away Junior Tafa with a heel hook in the first round of their UFC 305 pairing.

“Actually, there were no big changes,” Walker told Sherdog.com. “It was just about losing weight. I felt very heavy in my first UFC fight. I weighed [273 pounds] on the day of the…