On Friday an MRI revealed a Grade 2 strain, which will keep him out for a "minimum" of four weeks, the club announced.
Beltre, 38, has been hampered by injuries all season long. He missed the team's first 51 games of the season while recovering from a right calf strain, and this latest injury calls into question whether the veteran's body is finally starting to break down after such a long and consistent career.
So far this season, Beltre is hitting .317 with 16 home runs and 66 RBI. He also registered his 3,000th career hit earlier in the campaign.
With Beltre out, it will likely result in slugger Joey Gallo seeing consistent playing time at the hot corner, as he did during Beltre's previous absence.
Although Gallo is one of the game's top power hitters, the Rangers are without some important dimensions when Beltre is out of the lineup since he is an on-base machine and still among the best defensive third basemen in baseball.