Minnesota Vikings safety Harrison Smith, the team’s leading tackler, has been downgraded and is now listed as out for the game against the Falcons at 1 p.m. Sunday at the Georgia Dome because of a knee injury, according to the Associated Press.

Smith leads the Vikings with 54 tackles this season.

He was listed as questionable on Friday, but the team said on Saturday that he will not play. Smith was injured last week against Green Bay. He missed the first two practices of the week, but was limited in practice on Friday.

Rookie cornerback Trae Waynes (ankle) was also downgraded to out after being listed as questionable on Friday.

The Vikings (7-3) and Falcons (6-4) are battling for playoff position in the NFC.

Losing Smith is a major blow for the Vikings, who give up 224.8 yards passing a game, which ranks sixth in the league.

He was expected to help provide coverage on Falcons wide receiver Julio Jones, who leads the league in receptions (89) and yards receiving (1,189).

Antone Exum Jr., a second-year player from Virginia Tech, is likely to replace Smith in the starting lineup, according to the Minneapolis Star-Tribune. He’s played in 24 NFL games, but it will be his first start.