Walker left his start Tuesday against the Nationals after 1.1 innings due to a sore right knee, Anthony DiComo of MLB.com reports.
The soreness stems from a debridement procedure Walker underwent in mid-January. While the outing was a major disappointment, as he gave up six runs while recording just four outs, he's still expected to make his first turn in the rotation, which lines up for April 11 against the Phillies. He probably won't be able to pitch particularly deep in that game, as his early exit Tuesday prevented him from building up his pitch count. Walker estimated that he'll likely be limited to around 60-to-65 pitches in his first regular-season start, if cleared to pitch, according to Tim Healey of Newsday.