The Red Sox will be without a pair of pitchers for the next couple of days. One the club had plenty of heads up, while the other’s absence has thrown the team’s weekend plans into disarray.

The club announced Friday that right-hander Brayan Bello is being placed on the paternity leave list, and right-hander Cooper Criswell is going to the COVID-19 injured list after testing positive for the coronavirus. Bello will be back Monday in time to make his next start, but Criswell was expected to start on Saturday, so now the club has to figure out a new plan.

To fill their spots on the roster, the club called up left-hander Cam Booser and right-hander Brad Keller from Triple-A.

Originally implemented during the height of the pandemic, players who go on the COVID injury list must sit out a minimum of seven days. Red Sox manager Alex Cora said he found out about Criswell’s COVID diagnosis on Friday morning, but after all the injuries the club has experienced, they have no choice but to move past it.

“It is what it is, we’ve got to move on,” Cora said. We’ve been on this trail the whole season and we’re not going to make excuses. We have a good team here, we have good arms here, and somebody will start tomorrow. He’ll be back when he comes back and he’ll be part of this but tomorrow we’ve have to figure it out.”

With Criswell sidelined the Red Sox have a couple of options for a starter on Saturday. One is Keller, who has started 116 games in his big league career and who has been a regular fixture in the Worcester Red Sox rotation for the past month. He last pitched on Aug. 3, meaning he’d be available if called upon.

The Red Sox could also opt for a full bullpen game, starting with an opener and mixing and matching from there. One thing the club likely won’t do, Cora said, is call up Quinn Priester, the 23-year-old right-hander who was recently acquired in the Nick Yorke trade.

Ball in Casas’ court

Triston Casas (torn cartilage in ribcage) was set to play his eighth game in Worcester since starting his rehab assignment on July 30. Entering Friday he’d batted .286 with an .839 OPS, and Cora said he’s reached the point where he’ll be activated when he feels he’s ready to go.

“Right now it’s up to him. He’s healthy, he’s been taking grounders for a long time, I think the baseball part of it, the physical part of it, he’s ready to go. Now the timing of it, he’ll let us know,” Cora said. “He’s been hitting the ball hard, he’s coming back from his injury and we knew it would take time, but at one point it’s going to end. We’ll talk about him today, see how he does over the weekend and we’ll see where we’re at next week, but one thing is for sure, he’ll be part of this and we’re excited to get him back.”

Casas’ rehab assignment is due to expire on Aug. 18, so barring any setbacks and if he isn’t activated in the meantime, the latest he could return is for the start of the Red Sox upcoming road series against Houston.

Extra innings

Right-hander Justin Slaten (right elbow inflammation) is playing long toss up to 105 feet. The hope is he can get on the mound and throw a bullpen session later this week. … Nick Pivetta (fatigue) played catch on Friday and is scheduled to throw a bullpen Monday. If all goes well he could start either Wednesday against Texas or Thursday against Baltimore. … Liam Hendriks (Tommy John rehab) is throwing his second live batting practice on Saturday. He’ll have three total before starting a rehab assignment.