CHICAGO — Boston ace Chris Sale has tested positive for COVID-19 again, sidelining the left-hander while the Red Sox fight for positioning in the crowded AL playoff picture.

Sale had been scheduled to start Sunday in Chicago against the AL Central-leading White Sox. The seven-time All-Star also had a a mild bout with COVID-19 in January that required him to quarantine for two weeks.

“At this point, nothing shocks me, to be honest with you,” Manager Alex Cora said Friday. “On a daily basis we just go through a process and we just hope for good news. This is where we’re at.”

The Red Sox have placed 17 players on the COVID-19-related injury list since Aug. 3, including infielders Xander Bogaerts and Christian Arroyo and pitchers Nick Pivetta, Matt Barnes and Martín Pérez. Bogaerts was reinstated Friday and returned to the starting lineup against the White Sox. Left-hander Darwinzon Hernandez was activated from the 10-day injured list after being sidelined by a right oblique strain, and right-hander Kaleb Ort was promoted from Triple-A Worcester.

The Red Sox also placed infielder Jonathan Araúz on the COVID-19 list, and lefty Austin Davis went on paternity leave. The move with Araúz is precautionary; he has some symptoms, but he has tested negative multiple times, according to the team.

The 32-year-old Sale missed all of last season recovering from Tommy John surgery. Since returning Aug. 14, he is 3-0 with a 2.52 ERA.

“It’s unfortunate, but he’ll be back,” Cora said. “He feels good. He actually feels great, and hopefully he can come back right away, right after his X amount of days.”

Sale likely will have to stay away from the team for at least 10 days, though Major League Baseball has made exceptions for individuals cleared by its medical experts, based on not being infectious.

Any prolonged absence for the lefty would be a big blow for the Red Sox, who entered Friday with a one-game lead over the New York Yankees for the AL’s top wild-card spot. Toronto was another half-game back as it tries to overtake its AL East rivals for the second wild card.

“This is our reality and we’ve got to keep going,” Cora said.

Cora said Pivetta is feeling good, and he is one option when it comes to replacing Sale on Sunday. Right-hander Connor Seabold is on the team’s taxi squad for its road trip and could make his big league debut this weekend.

Pérez was in Worcester on Friday, and Cora said the plan was for him to throw a bullpen session and then pitch in a game on Sunday.