Cruz, who ran on the field and participated in drills, is not in the lineup for the Rangers' series opener and is listed as day-to-day.
On Thursday, general manager Jon Daniels said Cruz had an MRI and it showed the injury was in a different spot than the strain on his right hamstring that forced him to the DL earlier in the season.
Cruz has been one of the club's most productive offensive players this season. He's third in the early All-Star voting and is second on the team with a .330 batting average, 10 homers and 34 RBIs.
Cruz, who turns 30 on July 1, was placed on the 15-day disabled list April 27 with a strained right hamstring and returned May 14 in Toronto. Since returning to the lineup, Cruz is hitting .341 (15-for-44) with seven doubles, three homers and 17 RBIs in 12 games.