Gallo was placed on the 10-day injured list Sunday. He consulted with New York Yankees right fielder Aaron Judge, who has been out with a similar injury since April 20.
The strain is on the back side of the left-handed hitting Gallo’s swing while Judge’s injury is to his front side.
"I talked to Judge yesterday because I was concerned," Gallo said before Sunday’s game against Kansas City. "I was trying to figure out what he felt, ’cause at the time I didn’t have the MRI. He said, yeah, it’s better to be on the back side. His was more significant."
Gallo has 17 homers and was tied for second in the AL entering Sunday. His .653 slugging percentage topped the AL.
Rangers manager Chris Woodward said he thought Gallo will miss about two weeks.
"He worries me just because he creates so much torque with his body and he’s so strong that we don’t want him to come back too early," Woodward said. "We don’t want that to turn into a six- or eight-week deal."
Woodward said Gallo, who is 6-foot-5 and 230 pounds, probably will be able to bat before he can return to the outfield.
Gallo left Saturday’s game in the fifth inning, an inning after hitting his second homer in two days. He was pulled with a full count after speaking with Woodward and head athletic trainer Matt Lucero.
Galo felt the injury in the top of the inning when he prepared to throw from centre field to third base.
"It’s not like an excruciating pain," he said. "Just an annoying kind of, little nagging thing."
Centre fielder Delino DeShields was recalled from Triple-A Nashville.