The New York Yankees placed designated hitter Alex Rodriguez on the 15-day disabled list on Thursday with a strained right hamstring.
A-Rod had an MRI on Thursday morning after injuring his hamstring in Wednesday night's 4-1 loss to the Baltimore Orioles.
The 40-year-old left the game after he grabbed at his right hamstring while running out a grounder in the fifth.
"I feel sore," Rodriguez said after the game.
"I don't know. I don't want to speculate. It wasn't a big pop. I am hoping for the best. It's extremely frustrating. I was looking to come to Baltimore and continue what I started in Texas and Boston."
Rodriguez is struggling this season, hitting .194 with five home runs and 12 RBIs.
He is in the next-to-last season of his 10-year, $US275 million ($A367 million) contract, and is being paid $US21 million this year and next.
In March, Rodriguez announced he is planning to retire at the end of the 2017 season after playing out his contract.
The Yankees also recalled left-handed reliever James Pazos from Triple-A Scranton/Wilkes-Barre.
Pazos has a 3.00 ERA with 12 strikeouts in 12 innings at Triple-A.