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KANSAS CITY, Mo. — Kansas City Chiefs safety Tyrann Mathieu has been placed on the COVID-19/reserve list, the team confirmed.

NFL Network’s Tom Pelissero reports that Mathieu has tested positive for COVID-19.

The news comes just 11 days before the Chiefs’ season opener against the Cleveland Browns on Sept. 12. Mathieu, who is vaccinated, could be good to go for Week 1 as long as he can clear the NFL’s COVID-19 protocol.

Vaccinated players or staff who test positive and have no symptoms can return to the team after two negative COVID tests 24 hours apart. Meanwhile, unvaccinated players and staff who test positive are required to isolate for 10 days.

Chiefs head coach Andy Reid said over 90% of his team is vaccinated against COVID-19.

If Mathieu were forced to miss next weekend’s game for some reason, the Chiefs have Juan Thornhill and Armani Watts to fill in.

Mathieu is going into the final year of his contract with the Chiefs. The two-time All-Pro has been in negotiations with the team for a contract extension all offseason, but so far the two sides haven’t come to an agreement.