AP Photo KANSAS CITY QUARTERBACK Patrick Mahomes leaves the game after being injured against the Denver Broncos during the first half Thursday.

DENVER (AP) — Now the wait begins to see how long it takes Patrick Mahomes to return from a gruesome right knee injury.

Waiting in the wings, just in case: 35-year-old backup Matt Moore.

Mahomes, the MVP quarterback of the Kansas City Chiefs, was hurt on a second-quarter sneak in a 30-6 win over the Denver Broncos on Thursday night.

Kansas City coach Andy Reid doesn’t yet know how long Mahomes may be sidelined as the Chiefs (5-2) snapped a two-game skid with Moore stepping in and the Chiefs defense stepping up (nine sacks and a defensive score).

“We need time to evaluate,” Reid said. “I’ll leave it at that.”

Facing fourth-and-short deep in Denver territory, Mahomes picked up a first down by sneaking through the line.

As the pile began to clear, Mahomes didn’t jump up.

Struggling to straighten his right knee, he tossed his helmet to the side and covered his face with both hands. His teammates immediately checked on him. Seeing Mahomes’ condition, receiver Tyreek Hill put his hands on his helmet in concern — a feeling shared by a legion of Chiefs fans. Mahomes is a big reason why Kansas City was a preseason favorite to reach its second straight AFC championship game.

Broncos cornerback Chris Harris Jr. showed his respect by coming over and shaking Mahomes’ hand.

“You looked at it and were like, ‘Oh no, there is something wrong with him,'” Chiefs tight end Travis Kelce said. “You just hope a guy isn’t injured that bad and can come back.”

The reigning MVP was 10 of 11 for 76 yards before his injury. Moore finished 10 of 19 for 117 yards and a 57-yard TD strike to Hill in the third quarter.