Yastrzemski was removed from Friday's game against the Rockies due to right knee soreness, Susan Slusser of the San Francisco Chronicle reports.
Yastrzemski went 1-for-3 with a three-run homer, a walk and a strikeout to begin Friday's contest, but he was replaced defensively in the bottom of the ninth inning. He's considered day-to-day, and Steven Duggar and Austin Slater could see increased playing time if the 31-year-old is forced to miss additional time.