MILWAUKEE -- Brewers manager Craig Counsell expressed “concern” for the first time Monday about Ryan Braun’s availability for Friday’s Opening Day, before Braun missed a sixth straight day of intrasquad action.

What’s sidelining the longest-tenured Brewers player? Counsell previously had described it as the normal aches and pains associated with a 36-year-old Major Leaguer, but on Monday he was more specific. Braun further clarified that the issue is primarily his left side, and he tamped down speculation that his absence was somehow related to deliberation about whether to play this season.

“I understand the speculation, but I have no plans to opt out. I’m 100% planning to play,” Braun told MLB.com via text message. “Just working through a slight oblique issue before I can play in games.”

Braun has received regular treatment for core issues for years, especially since undergoing back surgery in the 2015-16 offseason. He played in the Brewers’ earlier scrimmages, but has not appeared since the start of the team’s “Blue-Gold Series” last Tuesday.

“Past today, it’s two [exhibition] games in three days before the season,” Counsell said. “So I don’t know where we’re going to end up there. I’m starting to get concerned, for sure. We’ll see how he responds today. He was better [Sunday]. It’s kind of back, oblique, neck, all throughout his upper body.

“So, I don’t know. We’re just going to have to wait and see how he responds today. We definitely need to have a day with marked improvement to be on track [to be active on the Opening Day roster]. And it also could be a scenario where he’s not ready for Opening Day, but he’s ready shortly after. That could be a scenario, too.”

Braun hasn't missed an Opening Day game since breaking into the big leagues in May 2007.

Anderson to injured list
The Brewers placed left-hander Brett Anderson on the 10-day injured list Monday with a blister, ruling out Anderson for his scheduled debut on Saturday against the Cubs. Anderson’s most recent intrasquad start was cut short after two innings when he began to develop the blister on his left index finger. It has been a common problem in past Spring Trainings, Anderson said.

“It’s improving, but our concern is a little bit the bigger picture here, and having it linger and affect him for multiple starts,” Counsell said Monday morning. “We’ve got a decision to make today. He did play catch yesterday. It went OK. We’ll see how it responds today, and then we’ll make a decision.”

Hours later, the Brewers formally made the IL move. Because they were able to backdate the assignment three days before the start of the Major League season, Anderson will be eligible to return as early as July 31, Milwaukee’s home opener against the Cardinals.

As for his spot on Saturday against the Cubs, among the Brewers’ options is right-hander Corbin Burnes on regular rest. Burnes threw 65 pitches over five innings in Monday’s intrasquad game at Miller Park.

More injury matters
• Reliever Ray Black was to be examined Monday morning by head team physician Dr. William Raasch after leaving Sunday’s intrasquad game with right shoulder tightness. The injury puts Black “in jeopardy” of beginning the season on the injured list, Counsell said.

• Left-hander Eric Lauer’s one-inning start in Sunday’s intrasquad game -- three up, three down, three strikeouts -- “was the highlight of the day,” Counsell said, but the left-hander will run out of time to make the Opening Day roster. Lauer got a late start because he’d come in close contact with an individual who tested positive for COVID-19. While Lauer never tested positive himself, the timing of that contact and protocols for players in such circumstances meant he was about a week behind the other pitchers. Lauer will make his next appearance Wednesday at the Brewers’ alternate training site in Appleton, Wis.

“He’s going to miss by a little bit, but I think what we’re seeing is he’s not going to miss by a lot,” Counsell said. “We’re going to have longer outings with him. The Appleton scenario allows us to do that and control it really good.’’

Last call
Josh Lindblom’s final tune-up start will be Wednesday in Appleton, Counsell said, ruling out Lindblom for the Brewers’ third game of the regular season at Wrigley Field. It appears Lindblom will instead make his Brewers debut in the next series at Pittsburgh. Lindblom mostly pitched in Korea for the past five years, though he did appear in four games with the Pirates in 2017.

With Anderson questionable because of the blister and Lindblom out of the picture for the Opening Series, Corbin Burnes and Freddy Peralta have a chance to open the season in the rotation. Each is lined up at the moment, Burnes for Game 2 on Saturday if needed, and Peralta for Game 3 on Sunday.