Vikings running back Dalvin Cook has been ruled out for Sunday's game against the Falcons after he was sidelined from practices this week because of a groin pull suffered in last week's loss at Seattle.

Cook is one of two starters ruled out for the Vikings offense against Atlanta. Right guard Dru Samia did not practice Thursday or Friday because of a wrist injury that popped up midweek, and he will be sidelined, meaning the Vikings will start a third different offensive line combination in the sixth game.

Receiver K.J. Osborn and cornerback Kris Boyd also will not play against the Falcons because of hamstring injuries. Cornerback Holton Hill (foot) is listed as doubtful.

Running back Alexander Mattison, who had a career-high 20 carries for 112 rushing yards in relief of Cook at Seattle, will get his first NFL start.

Cook, the NFL's leading rusher with 489 yards, will get at least two weeks' rest with the Week 7 bye. When asked whether Cook is expected to play against the Packers on Nov. 1, head coach Mike Zimmer responded, "How would I know? I'm just trying to do today and this week."

The Falcons defense has been vulnerable, allowing 32.2 points per game, but a new interior offensive line starter — possibly second-round rookie Ezra Cleveland or veteran Brett Jones, who got reps at guard this week — will face one of the NFL's best defensive tackles in Atlanta's Grady Jarrett.

"He's a great player, very quick, very powerful," Zimmer said. "They've got a lot of weapons, bring five guys a lot of times, play a lot of single-high [safety] and man-to-man, so it will be a good test for us. They'll have extra guys in the box for us, for sure."

Kickoff remains scheduled for noon at U.S. Bank Stadium after the Falcons reopened facilities Friday morning in Flowery Branch, Ga., when Thursday's COVID-19 tests returned negative. The NFL closed Atlanta's facilities on Thursday, after Wednesday's tests turned up a second confirmed positive for the week.

All-Pro receiver Julio Jones will return to the Falcons lineup, as he was not listed with a gameday designation on Atlanta's injury report. He has played just 15 snaps since aggravating a hamstring injury in Week 2.

The Falcons ruled out defensive end Takk McKinley (groin) and safety Jaylinn Hawkins (concussion).

Reiff: 'Grateful to be here'

Left tackle Riley Reiff spoke to reporters Friday for the first time since accepting a $5 million pay cut in September to stay with the Vikings as the team sought salary cap space after acquiring defensive end Yannick Ngakoue. Reiff, a 31-year-old team captain, said his decision, which came after a day away from practice, landed on factors outside of the money.

"My teammates, coaches. I love playing here in Minnesota," Reiff said. "Midwest, tough. I like this division. I'm grateful to be here."

Reiff, who said Friday he just takes his playing career "hour by hour," has one non-guaranteed year left in his contract after this season, but the restructured deal gives the Vikings a deadline of March 18 when a $5 million roster bonus is due. The ex-Lions left tackle has started 52 of 57 games since signing with Minnesota as a free agent before the 2017 season.

"What he did to come back to the team, that just shows how much he wanted to be here," said safety and team captain Harrison Smith, "and how important he is to us."

'Crucial Catch' game

The Vikings will honor those affected by all forms of cancer during Sunday's game, the team's only home game in October, which is the NFL's "Crucial Catch" month.

Chris Doleman, who died in January from brain cancer and would've turned 59 years old Friday, will have his Hall of Fame bust and jacket displayed by his Ring of Honor plaque in U.S. Bank Stadium. Fullback C.J. Ham's mother, Tina, who died in May from pancreatic cancer, also will be among those honored.

Erika Rucks, a pediatric oncology nurse at the University of Minnesota's Masonic Children's Hospital who has battled through Hodgkin's lymphoma and breast cancer, will sound the Gjallarhorn before kickoff.