LONDON -- Washington Commanders quarterback Marcus Mariota left Sunday's game against the Indianapolis Colts with a right knee injury that he suffered on the second series of the game.
Mariota was replaced by rookie seventh-round pick Athan Kaliakmanis, who was playing his first NFL snaps. Mariota was ruled out during halftime.
The injury was even more damaging because Mariota was playing in place of Commanders franchise quarterback Jayden Daniels, who missed his second consecutive game because of a dislocated left elbow.
Mariota's right knee appeared to bend as he was sacked by defensive tackle Adetomiwa Adebawore on third-and-goal from the 6-yard line. Mariota did walk on his own into the locker room after being examined in the medical tent.
Mariota suffered a sprained right MCL during the Commanders' preseason opener. He missed the rest of the preseason but was ready to play by Week 1.
Washington was already without top wide receiver Terry McLaurin (hamstring), who did not play after getting hurt in practice Friday, and starting right guard Sam Cosmi for a second game.
Defensive end Charles Omenihu (groin) was also ruled out during halftime, and wide receiver Jaylin Lane was carted off in the third quarter after suffering a left ankle injury during a kickoff return.
Mariota led Washington to a 33-31 win over the Seattle Seahawks last week, throwing for 183 yards and three touchdowns. He threw for 46 yards and had a 35-yard run on a zone-read keeper Sunday to set up a field goal.
He is in his third season with Washington and has started 10 games.