A Washington Nationals player tested positive for the coronavirus and five others — including four players and a staff member — are quarantining after contact tracing, General Manager Mike Rizzo announced Wednesday.

Rizzo did not identify the player, disclosing only that the Opening Day roster will be affected by the positive test and contact tracing. The Nationals are scheduled to begin their season Thursday against the New York Mets with first pitch set for 7:09 p.m. Rizzo added without hesitation that the game will be played.

The Nationals had no coronavirus cases throughout the past six weeks of spring training in West Palm Beach, Fla., according to Rizzo. The team learned of the positive test in the early hours of Wednesday morning. The infected player was tested Monday along with teammates, coaches and staff members at the club’s facility in Florida as part of MLB’s every-other-day testing model that started in July. Following Monday’s tests, a majority of those at spring training took a charter flight to Washington that night.

The player who tested positive was on the team charter, according to two people with knowledge of the situation. After learning of the positive result, Nationals players, coaches and staff took both PCR and rapid tests. Since Monday’s tests, there were a number of chances for the player to be in contact with teammates, coaches or staff: The Nationals worked out Monday and played their exhibition finale against the Houston Astros. They then took buses to their flight, flew from West Palm Beach to Dulles International Airport, then bused from Dulles to Washington.

Asked whether he was concerned about subsequent positive tests stemming from the charter, Rizzo repeated that the team was tested again Wednesday and will know more once they have their next round of results. The team was off Tuesday and canceled Wednesday’s workout in the early afternoon.

“First and foremost, we want to protect our players, their families and our staff members,” Rizzo said. “That’s always paramount in my mind, and then we’re going to put the best, most qualified group of players on the field to win a baseball game. The good thing about this year is it’s 162.

“And a little hiccup, a little bump in the road, and we’re going to handle this like we handle everything else.”

Potential outbreaks have been far less frequent than when the teams reassembled nine months ago. On Friday, ahead of the final weekend of spring training, MLB announced it had 17 positive tests out of 72,751 conducted. In the following days, though, both the Nationals and Boston Red Sox have had to scramble and contact trace.

Red Sox reliever Matt Barnes tested positive for the coronavirus Saturday. Rizzo and the Nationals then received their own distressing news. Both instances show the risks of playing another season amid the pandemic. As the country seeks to reopen, and the Nationals welcome up to 5,000 fans for Opening Day, health experts warn of another wave in cases even as millions are vaccinated daily.

Rizzo did not specify whether the Nationals player who tested positive is symptomatic. According to MLB’s operations manual for 2021, a player who tests positive and is symptomatic has to isolate for at least 10 days following the first sign of symptoms. A person who tests positive and is asymptomatic has to isolate for at least 10 days following the initial positive PCR test. A person who was in close contact with an infected individual has to quarantine for at least seven days. To return to club facilities or travel with the team, that person has to test negative through a PCR test on Day 5 or later. be asymptomatic and continue daily testing for 10 days following the potential exposure.

Following Centers for Disease Control and Prevention guidelines, the operations manual states that close contact is “being within six feet of an infected person for a cumulative total of 15 minutes or more over a 24-hour period starting from two days before illness onset until the time the individual is isolated.”

Max Scherzer, who is scheduled to face the Mets on Thursday, said he was not on the charter flight because he traveled north with his family. The four players in quarantine, however, will not be available to play Thursday night or in the immediate future.

The team will thus need a small handful of players from their alternate site in Fredericksburg, Va. They are calling up 20-year-old infielder Luis García, according to two people with knowledge of the roster move. They are also calling up left-handed reliever Sam Clay, outfielder Yadiel Hernandez and catcher Tres Barrera, according to people with knowledge of those moves. Most alternate site players flew with the team from West Palm Beach before heading to Fredericksburg.

“This is the reason you have 60 good players in the organization, to kind of prepare for these type of fail-safe scenarios,” Rizzo said. “No matter how many people we have to protect and put into covid protocol, we’re going to reach down and grab some really good players to help us beat a really good New York Mets team tomorrow night.”

This marks the Nationals’ second straight Opening Day that will be clouded by a positive test. In July, just hours before first pitch against the New York Yankees, Rizzo announced that star outfielder Juan Soto tested positive and would miss the beginning of the season (Soto later insisted it was a false positive). Soto was sidelined for eight games and returned in early August.

Scherzer took the mound when the Nationals were last surrounded by such uncertainty. Now he will do so again.

“We had seen so few positive cases across spring training as a whole,” Scherzer said Wednesday. “It just shows you how quickly that can turn. It can turn on a dime. We have to face it, and we have to overcome it.”