TAMPA — The Washington Commanders placed quarterback Marcus Mariota, slated to back up Jayden Daniels, on the injured reserve list and signed former Notre Dame quarterback Sam Hartman to the active roster.

Mariota suffered a strained pectoral muscle in practice after missing the last two preseason games because of a groin issue.

Jeff Driskel now becomes Washington’s backup behind Daniels, who will make his first start at Tampa Bay Sunday.

Washington signed Mariota to a one-year deal in March. The Commanders valued his experience with 74 starts in nine seasons. Also, he has bonded with Daniels — both were No. 2 overall picks and Heisman winners.

Driskel has a strong training camp to make Washington’s 53-man roster. Like Daniels and Mariota, Driskel showed he could make plays on the move.

Coach Dan Quinn said he noticed a big difference in Driskel after the spring workouts, owing to his increased comfort in coordinator Kliff Kingsbury’s offense.

“He could really let it rip,” Quinn said. “I’ve known him for a long time, I know the competitor, but it’s his legs and athletic ability that kind of sets him apart.”

Washington signed Hartman as an undrafted free agent in the spring. The Commanders cut him on Aug. 26 but signed him to the practice squad the next day.