​The Washington Commanders are going through a terrible run of injury luck. In Sunday’s loss to the Indianapolis Colts, quarterback Marcus Mariota, playing in place of the injured Jayden Daniels, looked outstanding early, getting the Commanders into the red zone on their first two possessions. At the end of that second possession, Mariota was sacked, injuring his knee, and he did not return. It was his second start since Daniels went down with a dislocated elbow in Week 2. Mariota led the Commanders to a big upset over the Seattle Seahawks in Week 2. Suddenly, Washington was down to its third quarterback, rookie seventh-round pick Athan Kaliakmanis. Mariota’s injury certainly looked season-ending. Of course, that means nothing. Daniels’ injury looked even more serious than it was, and he could be back in three weeks. During the game, Molly McGrath of the NFL Network said Mariota was believed to have suffered an MCL injury. That was the extent of the details. Back in Washington’s preseason opener in August, Mariota suffered a sprained MCL. “He does have a right knee MCL sprain,” head coach Dan Quinn said at the time. “It will knock him out for the rest of the preseason. Optimistic that he’ll be ready for the start of the regular season.”After Sunday’s game, Quinn confirmed it was an MCL, but he didn’t reveal anything further. “The team thinks it’s an MCL injury,” Quinn said. “When we get the scan tomorrow, we’ll have further knowledge of what we’re dealing with and length and all those.”When the Commanders return to Virginia, Mariota will undergo further testing to determine the severity. The good news is Washington expects Daniels back next week, but Kaliakmanis could be Daniels’ backup for the foreseeable future. This article originally appeared on Commanders Wire: Commanders’ Dan Quinn provides update on Marcus Mariota’s knee injury