New England quarterback Cam Newton tested positive for the novel coronavirus, and the NFL postponed the Patriots’ game at the Kansas City Chiefs that had been scheduled for Sunday afternoon.

The NFL announced Saturday that the Patriots-Chiefs game is now slated to be played Monday or Tuesday, and it attributed the postponement to positive coronavirus tests on both teams. It was the second NFL game scheduled for Sunday to be postponed, with this week’s outbreak on the Tennessee Titans having led to their game in Nashville against the Pittsburgh Steelers being pushed to Week 7.

The NFL said in a statement that the Patriots and Chiefs were working with the league and the NFL Players Association, in consultation with infectious-disease experts, to “evaluate multiple close contacts, perform additional testing and monitor developments.” The NFL also said, “All decisions will be made with the health and safety of players, team and gameday personnel as our primary consideration.”

Newton’s positive test was confirmed by a person familiar with the situation. The Patriots confirmed that one of their players tested positive but did not identify him.

“Late last night, we received notice that a Patriots player tested positive for COVID-19,” the team said in a statement Saturday. “The player immediately entered self-quarantine. Several additional players, coaches and staff who have been in close contact with the player received point of care tests this morning and all were negative for COVID-19.”

Additional test results that returned Saturday night produced no more positives for the Patriots, according to a person familiar with the results. The league was expected to wait for more test results to arrive Sunday before making a final decision about the game, but it might lean toward playing Monday if there are no more positive tests.

The Patriots had been scheduled to travel to Kansas City on Saturday but said they had delayed the trip pending consultation with the NFL.

“We are in close consultation with the NFL, as well as our team of independent doctors and specialists, and will follow their guidance regarding our scheduled trip to Kansas City and game against the Chiefs,” the Patriots said in their statement. “The health and safety of our team, as well as our opponent, are of highest priority.”

The Chiefs were placing practice squad quarterback Jordan Ta’amu on their covid-19 reserve list, the team confirmed, after he reportedly tested positive. Chiefs safety Tyrann Mathieu wrote Saturday on Twitter, “Wear your mask, wash your hands.”

Newton, the 2015 NFL MVP for the Carolina Panthers who signed with the Patriots in July, is the league’s most prominent player to test positive. He took over for six-time Super Bowl winner Tom Brady, who left in March to sign with the Tampa Bay Buccaneers, as the Patriots’ starter and was impressive while leading them to two victories in their first three games.

Newton’s positive test comes with the NFL dealing with its first outbreak this season. Three more members of the Titans — one player and two team staffers — tested positive in results that returned Saturday. That brought the total positive tests for the Titans this week to 16 — eight players and eight other members of the organization.

The league first said the Titans’ game this week against the Steelers would be played Monday or Tuesday, then announced the postponement to Oct. 25 after more positive tests for the Titans. That was the first postponement of the season as the NFL operates during the pandemic with teams based in their home cities, practicing in their own facilities and playing home games in their own stadiums. The first three weeks were completed with few positive tests and no disruptions to the schedule.

An unidentified player missed his team’s game in Week 2 after testing negative but exhibiting symptoms. The Atlanta Falcons’ game Sept. 27 against the visiting Chicago Bears was played after Falcons rookie cornerback A.J. Terrell tested positive in results returned the day before the game.

“I think this is something we’ve been preparing for from the very beginning of our preparations,” Allen Sills, the NFL’s chief medical officer, said in a phone interview Friday, before Newton’s positive test and the Patriots-Chiefs postponement. “As we’ve said repeatedly, we expect to have new positive cases. No matter how careful everyone is or how stringent our protocols are, as long as this disease remains endemic in our society, it’s going to be extraordinarily difficult, if not impossible, to avoid any new positive cases.

“So that’s why our focus has never been on elimination of the virus because we just know that’s medically impossible. Instead, we’ve focused on mitigation, which means when we do have a positive case that we try as best possible to prevent spread within any of our team communities or our league as a whole. The [Titans’ outbreak is] exactly why we planned and put the protocols in place that we have. We had a plan and a preparation there to walk through when this unfolded.”

The Titans’ facility remains closed, and Sills said Friday it will not reopen until the league is “convinced that we’ve reached the end of the transmission event that occurred earlier this week and that we have put in place all the measures to keep everyone safe there.”

The Minnesota Vikings, who hosted the Titans last week, reopened their facility Thursday under enhanced health and safety protocols. The Vikings again had no positives in test results returned Saturday, according to a person familiar with them. The Vikings have had no positive tests this week, and the NFL plans for the Vikings-Texans game to be played as scheduled Sunday in Houston.

NFL players, coaches and certain team staffers are tested for the coronavirus daily, except on game days, under protocols developed by the league and the players’ union. After the outbreak on the Titans, the league informed teams of enhanced protocols for teams experiencing an outbreak or exposed to one. Those protocols include daily point-of-care tests in addition to the regular testing, including game days, and a mask-wearing requirement for players, coaches and staffers on the practice field.

The enhanced protocols say players on those teams also should wear gloves on the practice field, with the exception being a quarterback’s throwing hand. And players are prohibited from gathering away from a team’s facility.

The league and the NFLPA have extended their regular daily testing indefinitely. That testing program now covers players and coaches while teams are on their bye week. The NFL has imposed heavy fines on head coaches and teams — $100,000 per coach and $250,000 per team — for violations of its directive that coaches and staffers must wear face coverings properly on the sideline during games. Players do not have to wear masks on the sideline except in the few cities where that’s required under local guidelines.

The NFL previously left open the possibility of switching to a bubble format, as the NBA, NHL and WNBA have done this year, for the postseason. And some have argued the NFL should consider having teams require players, coaches and staffers to stay in a hotel instead of going home from the team facility every day.