Mariota left the first quarter of Thursday's preseason game against the Dolphins due to an apparent right knee injury, Nicki Jhabvala of The Washington Post reports.
Mariota may have picked up the injury when he was hit by Tyrel Dodson right after a pass to Dyami Brown. Mariota initially stayed in but was favoring his right leg after handing the ball off to Kaytron Allen, and the veteran quarterback has gone to the locker room to undergo further tests, per Jhabvala. Sam Hartman has taken over as the Commanders' quarterback following Mariota's departure.