Harrison Smith ruled out vs. Falcons

MINNEAPOLIS -- The Vikings have ruled Harrison Smith out for Sunday's game against the Falcons, meaning they'll try to contain Julio Jones and Atlanta's prolific passing attack without the help of their best safety.

Smith suffered a left knee injury Sunday when he collided with cornerback Terence Newman in the first quarter of the Vikings' loss to the Green Bay Packers. He was listed as questionable on the team's injury report Friday after practicing on a limited basis, and he said he was going to do his best to take care of his knee between then and Sunday.

After the Vikings' final walk-through Saturday, however, they downgraded Smith, who will not travel with the team to Atlanta.

Without him, the Vikings will have to work even harder to slow the league's fifth-ranked passing attack. Second-year safety Antone Exum will make his first career start on Sunday, according to a league source, as the Vikings look for a safety who can help in coverage.

Otherwise, the Vikings would turn to Robert Blanton, who started most of last season next to Smith before losing his job to Andrew Sendejo.

In any case, dealing with Jones, who leads the league with 89 catches, already figured to be a tough task. The absence of Smith -- who tied for third in the league with five interceptions last season -- could be a significant loss for the Vikings.

Vikings rookie cornerback Trae Waynes also was downgraded to out with an ankle injury that limited him in practice on Thursday and kept him out on Friday.