The Los Angeles Rams placed cornerback Jalen Ramsey and tight end Tyler Higbee on the reserve/COVID-19 list on Monday. Neither will be available for Monday's game against the Arizona Cardinals.

They join running back Darrell Henderson, cornerback Donte Deayon and offensive lineman Rob Havenstein, who were previously placed on the COVID list. It's not clear why they were placed on the list, which could indicate a positive COVID-19 test or a close contact with somebody who tested positive.

The transactions are a tough blow for an 8-4 Rams team looking to get back on track against the first-place Cardinals after dropping three of their last four games. Ramsey is a four-time Pro Bowler and the Rams' top secondary defender. His presence will be missed against a Cardinals passing attack featuring quarterback Kyler Murray and wide receiver DeAndre Hopkins, both of whom returned last week from multi-week injuries.

Higbee is the Rams' No. 1 tight end and is third on the team behind wide receivers Cooper Kupp and Robert Woods with 44 receptions. The Rams continue to play without Woods, who suffered a season-ending ACL tear in November.

The Rams activated defensive backs Kareem Orr and Grant Haley and tight end Jared Pinkney among others from their practice squad in corresponding moves on Monday. They also activated linebacker Justin Hollins from injured reserve from a torn pectoral muscle sustained in Week 3.

The Cardinals beat the Rams, 37-20 in their Week 4 matchup and enter Monday's game with a two-game lead on their NFC West rivals at 10-2. They'll seek to remain a game ahead of the Green Bay Packers and Tampa Bay Buccaneers for first place in the NFC with a win Monday night.