Maybin said he suffered the injury running down the first-base line on a ground ball in the third inning. Maybin stayed in the game until the fourth inning, when manager Bud Black decided to pull him as a precaution.
Black said Monday that Maybin was still sore and that "we're hoping it resolves itself in the next couple of days."
The injury came into play during Monday's game when outfielders Ryan Ludwick and Chris Denorfia collided in the fourth inning. Ludwick, who was playing right field, later left the game, saying he felt woozy. Denorfia shifted from center field to right, while Will Venable entered in center.
Black said before the game that the team likely won't add an outfielder for the series against the D-backs that begins Tuesday at PETCO Park.
Maybin's average had risen to .283 when he exited the game Sunday, the highest that it had been since the second game of the season.
Overall, Maybin began Monday hitting .320 on the road this season, with five home runs and 22 RBIs in 172 at-bats, compared to .237 with one home run and five RBIs in 139 home at-bats. He had 14 hits and batted .538 while scoring eight runs last week, which propelled him to a share of the National League Player of the Week honors.