Polanco was injured while trying to catch Delwyn Young's pop single that landed just behind the mound in the second inning. Polanco's right foot came down hard on the mound as he lost the ball in the sun, and he fell to the ground. Two trainers helped him off the field.
Polanco was examined by the Pirates medical staff, which told him there was a sprain in the back of the knee as well as a slight hyperextension of the upper calf.
On Tuesday, manager Charlie Manuel said Polanco was day to day, and doctors found no significant issues with the knee. The injury is being described as a strain.
"I don't think it's too bad," Polanco said Monday. "When it first happens, you really get scared. You don't know what's happening. It doesn't feel right. But now that the doctor took a look at it, it's nothing big at all."
Philadelphia ace Roy Halladay gave up his first run in three spring training starts, striking out six and allowing three hits in five innings. when Pittsburgh went ahead 1-0 in the second inning on Ryan Doumit's double and Lastings Milledge's RBI single.
Information from ESPN.com's Jayson Stark and The Associated Press was used in this report.