The injury was not believed to be serious. Hamels was scheduled to take the mound Thursday in Minnesota.
General manager Jon Daniels said Tuesday, before the Rangers played the Twins, that one of two right-handers with Triple-A Round Rock, Chi Chi Gonzalez or Anthony Ranaudo, will be summoned to fill Hamels' spot. Gonzalez was the Rangers' first-round draft pick in 2013. Ranaudo made two starts earlier this season.
Hamels told reporters he felt the muscle grab in his previous start.