The slugger was lifted from Sunday's contest against the Yankees in the seventh inning and hasn't played since, but the team has yet to determine whether he will sit the final game of the season on Wednesday.
Manager John Farrell said Encarnacion feels the greatest amount of soreness in the area when he follows through on his swing.
"We will reevaluate him tomorrow. I can't give you a percentage of [whether] he will be in the lineup tomorrow or not," Farrell said.
Encarnacion has set career highs at the plate with 42 homers and 110 RBIs, with a .557 slugging percentage and .941 OPS, while splitting time at first base and designated hitter.
"He has, I think, performed his way and improved at that position to become a very good first baseman." Farrell said.