Boston relief pitcher Matt Barnes will be out at least 10 days after testing positive for COVID-19. Winslow Townson/Associated Press

With Opening Day on Thursday, the Red Sox have four additional players in quarantine after Matt Barnes tested positive for COVID-19.

The Sox learned of the positive test on Saturday when they received Barnes’ results from a Thursday test.

Sunday, they added four others to their list of players who would need to be quarantined for at least seven days from the point of contact until they test negative. For those in contact with Barnes on Friday or later, they’ll likely be ruled out for Opening Day.

The Red Sox aren’t saying the names of the players who were in close contact, but Chief Baseball Officer Chaim Bloom said it could be fairly obvious when it becomes clear which players haven’t been used in the final three spring training games.

Of the position players, there doesn’t seem to be any big names being held out, as every one of the projected starters either appeared in Saturday’s game or were written in the lineup for Sunday’s game. The only exception is Christian Vazquez, who is currently sidelined with an eye laceration.

Given Barnes is a reliever, it’s likely some pitchers may be the ones in jeopardy.

Matt Andriese was scratched from his start Saturday. Garrett Richards hasn’t started since last Tuesday, nor will he start one of the final three games. Nick Pivetta hasn’t started in a week and is also not in line to start before camp breaks.

Instead, it’ll be prospect Josh Winckowski starting on Sunday, Tanner Houck, who has already been sent down to the minors, starting on Monday, and Martin Perez starting the final spring game on Tuesday.

The Sox are optimistic the outbreak will be contained.

“Everybody who could was rapid tested yesterday,” Bloom said. “And we wanted to make sure we first did the players who were scheduled to play in the game, then got to as many other people as we possibly could through camp. I don’t know if every person was tested yesterday but a large number of people were and everybody came back negative, which was fantastic.”

Four additional players who were in moderately close contact with Barnes but don’t need to quarantine will have their workout schedules altered this week to avoid further contact with others.

Contact tracing in spring training is made easier by the use of monitoring devices that must be worn by all players and staff from the moment they enter the complex until they leave.

Bloom said he’ll keep his eye out for additional roster moves, but that’s normal for this time of year when final roster decisions are being made and players who are cut often get designated for assignment or passed through waivers.

The Red Sox are also encouraging their players who are eligible to get vaccinated.

“This has been an issue we’ve talked a lot about internally, wanting to make sure, without doing anything irresponsible from a standpoint as society at large or anything unethical, we are in a position to help facilitate guys who want to end up getting vaccinated as soon as they can,” Bloom said. “That is an ongoing process. Of course we also recognize in Florida we’ve got a lot of minor league players coming in very soon and a lot of minor league staff who are looking to start a season a month after that. We want to make sure we’re facilitating this for them.

“With Florida and Massachusetts, we’re doing everything we can to be informed and we know this is bigger than just us. This is about an entire society. We recognize we are just a small piece of that and we want to make sure we do it right.”

MARLINS: Highly regarded prospect Jazz Chisholm was declared the winner of the competition for Miami’s second base job, and he’ll be in the lineup on Opening Day.

Chisholm batted .268 with three homers and four stolen bases in spring training. He was competing with Isan Diaz, and won almost by default. Diaz went 2 for 34 and will start the season in Triple-A.

Chisholm, 23, was acquired in the 2019 trade that sent pitcher Zac Gallen to Arizona.

DIAMONDBACKS: Madison Bumgarner will make his second straight Opening Day start for Arizona, and Taylor Widener will fill the rotation spot of right-hander Zac Gallen, who has a hairline fracture in his right forearm after getting jammed during batting practice.