ST. PETERSBURG, Fla. -- Seattle Mariners starter Bryan Woo left in the fourth inning of Monday night's 4-3 loss at Tampa Bay with right hamstring tightness.
The right-hander was hurt on a pitch to Taylor Walls with a runner on first. He couldn't complete a warmup pitch after pushing off the rubber with his right leg, then was replaced by Tayler Saucedo.
Woo walked slowly off the mound to the dugout.
Mariners manager Scott Servais said Woo will have an MRI on Tuesday.
"We just have to see," Servais said, "It's hard to project anything. Hopefully it's a strain and he won't be out too long."
Woo allowed one run, five hits and struck out three. His ERA through eight starts this season is 1.77 to go with a 3-1 record.
The Associated Press contributed to this story.