Pittsburgh Steelers quarterback Ben Roethlisberger went down during the third quarter of Sunday’s game against the St. Louis Rams and was carted off the field with what looked to be a knee injury.

Rams safety Mark Barron dove at his legs and took him down by grabbing his left foot. Roethlisberger went down and took the sack, and took awhile to get up.

Roethlisberger limped off the field with the help of trainers, then eventually was carted off to the locker room. He got a handshake from teammate Darrius Heyward-Bey and it appeared on television that Roethlisberger was teary-eyed.

Michael Vick, who the Steelers signed during training camp, replaced Roethlisberger. 

Pass protection had been an ongoing problem for the Steelers, but their offensive line has been improving. Roethlisberger wasn’t sacked in the Steelers’ 43-18 win over the 49ers last week. In 2013 and 2014, Roethlisberger played in all 16 games in back-to-back seasons for the first time in his career.

That streak appears to be in serious jeopardy.