The Texans lost two of their best players during the first series of Sunday night's matchup against the undefeated Chiefs -- linebacker Whitney Mercilus left the field with a chest injury, and a few plays later defensive end J.J. Watt suffered a knee injury that will reportedly end his season.

Watt had to be helped to the sidelines and was taken to the locker room in a cart. He was later transported to the hospital in an ambulance where he was diagnosed with a tibial plateau fracture to his left leg. The Houston Chronicle's John McClain reports that Watt's injury will require surgery and that his season is over, though ESPN's Adam Schefter says the Texans aren't sure how long Watt will be sidelined.

Mercilus was quickly ruled out for the remainder of Sunday's night game as well.

Watt, who played in just three games in 2016 because of a back injury, came into Week 5 looking for his first sack on the season, though according to Pro Football Focus he still was the second-rated defensive end in the league behind only Aaron Donald. 

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