Guerra suffered a strain of the right calf while laying down a sacrifice bunt in the third inning of his April 3 Opening Day start against Colorado. He was placed on the 10-day disabled list a day later.
Guerra has accompanied the Brewers on their current road swing through Toronto and Cincinnati. Most of his work has been dedicated to maintaining arm strength, but Guerra began walking on a treadmill Saturday, according to Brewers manager Craig Counsell.
"He's doing really well," Counsell said. "Pretty much everything has been positive in his rehab so far."
Guerra said he expects to return to pitching "somewhere in the middle" of the originally projected 4-to-6 week recovery time.
"The next step would be running; then comes more agility work and then throwing off the mound," Guerra said.
• Tommy Milone (1-0, 7.36) has assumed Guerra's spot in the rotation. He worked five innings for the win Friday at Cincinnati. Counsell confirmed Milone will make his next scheduled start, Wednesday at Chicago.
• Catcher Andrew Susac (trapezius tightness) was reinstated from the 10-day disabled list Saturday and optioned to Triple-A Colorado Springs."We couldn't be happier with our catchers," Counsell said of Manny Pina and Jett Bandy.