Marquez was diagnosed with a right triceps injury after exiting his start in Wednesday's 4-1 loss to the Guardians, Patrick Saunders of The Denver Post reports. He's scheduled to undergo an MRI on Thursday in Denver.
Making his return Wednesday from a minimum-length stay on the injured list due to right forearm inflammation, Marquez (2-2) took the loss after giving up three earned runs on six hits and one walk while striking out four over 3.2 innings. Though he was laboring through the start, Marquez was expected to work deeper into the outing before he felt a "sharp pain" in his arm following his 58th and final pitch of the afternoon. While initial tests on Marquez's arm didn't show any significant damage nor an aggravation of the prior injury, the Rockies won't know the full extent of the issue until after the MRI is conducted.