Davis appeared to hurt himself on his final swing in the at-bat and walked gingerly back to the dugout. Gerardo Parra replaced Davis in left field.
"[I] took an awkward swing, knee over-rotated," Davis said.
When asked how serious the torn meniscus could be, Davis was unsure: "I can't really tell when they have to go in there and clean it up."
If Davis is to miss an extended period of time, it will be yet another blow to a Brewers team that has now lost seven games in a row.
First baseman Adam Lind will become the only Opening Day starter for the Brewers who will have been available for every game this season starting Sunday in the series finale against the D-backs. Five of those players have missed a week or more because of injury.
Should Davis be placed on the disabled list, it would open a spot on the roster for rookie starter Tyler Wagner. The right-hander will make his Major League debut on Sunday.
Davis has started 40 games in left field this season for the Brewers and entered Saturday's game on a four-game hitting streak (7-for-14). He's batting .250 with five home runs and 16 RBIs.
Brandon Curry is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.