Dalvin Cook has been placed on the reserve/COVID-19 list by the Minnesota Vikings.

The Vikings sit second in NFC North after improving to 7-7 with a 17-9 victory over the Chicago Bears on Monday, but have suffered a major blow ahead of their clash with Los Angeles Rams in Week 16.

Mike Zimmer's side face the 10-4 Los Angeles Rams on Sunday, however, they will now likely have to turn to Alexander Mattison to lead their rushing attack in a pivotal game.

Cook's absence would rob the Vikings, who currently occupy the third and final NFC Wild Card spot with three games left, of a back who leads the NFC, and ranks third in the NFL, with 1,067 rushing yards.

Cook, who has 226 carries and six scores on the season, joins numerous Pro Bowlers who have been added to the COVID-19 list this week, including the likes of Travis Kelce and Tyreek Hill.

Mattison, who was activated from the reserve/COVID-19 list on Wednesday, is the favourite to replace Cook as the starter, though Kene Nwangwu and Wayne Gallman are on the active roster and could see a share of the workload.

Mattison has three starts this season, in which he has totalled 26 carries for 112 yards, 25 carries for 113 yards, and 22 carries for 90 yards.

The Vikings have also activated wide receiver Dan Chisena from the COVID-19 list, while they have signed running back A.J. Rose Jr. to the practice squad.

The NFL's updated COVID-19 protocols have made it easier for players to return from the reserve/COVID-19 list, provided they are vaccinated, asymptomatic, and test negative twice within one day.

Players who are not vaccinated are subject to a mandatory 10-day quarantine, which leaves uncertainty whether Cook will be back in time to face the Green Bay Packers in Week 17.