SAN DIEGO -- The Padres' vaunted bullpen depth is getting an early test.

José Castillo, expected to be one of the team's most prominent lefty weapons, will miss significant time with a left lat muscle strain, Padres manager Jayce Tingler said. Castillo sustained the injury during an intrasquad game on Tuesday night.

"You feel bad for Castillo and all the work that he's put in," Tingler said. "We're going to need some good breaks in order for him to return to play this year. But we're going to stay optimistic."

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Tingler was hesitant to put a timetable on Castillo's return, given the uncertain nature of these types of injuries. Castillo was diagnosed with a Grade 2 tear of his left teres major muscle, attached to his lat in his upper back. The Padres skipper offered six weeks as the earliest possibility "based on what history has shown from those kinds of injuries."

It's the latest in a long line of tough breaks for Castillo, who missed nearly the entire 2019 season. He missed four months with a left elbow injury. Then, in his return to the mound, he sustained an injury to his left middle finger. Tingler said he didn't think the newest injury was related to either of those two ailments.

In his 2018 rookie season, Castillo posted a 3.29 ERA with 52 strikeouts in 37 appearances. Lefties Matt Strahm and Drew Pomeranz likely will be called upon to cover some of Castillo’s workload.

2021 schedule released
Major League Baseball unveiled its full schedule for the 2021 season, and the Padres' slate sure has a similar feel to the shortened '20 edition.

Like 2020, the Padres are set to open the '21 season at home against the D-backs (April 1-4), and they'll close the season in San Francisco (Oct. 1-3).

• Padres' 2021 regular-season schedule | 2020 schedule

The Padres' first series with the rival Dodgers comes April 16-18 at Petco Park. They'll play two series in Los Angeles down the stretch in September.

On the Interleague docket are road series against the Rangers (April 9-11), Astros (May 28-30), A's (Aug. 3-4) and Angels (Aug. 27-28) and home series against the Mariners (May 21-23), A's (July 27-28), Astros (Sept. 3-5) and Angels (Sept. 7-8).

Worth noting
• Pomeranz, who planted awkwardly after throwing a pitch Sunday night, won't miss his next scheduled outing, Tingler said. Pomeranz exited the intrasquad game Sunday and received treatment on his right knee, but that was mostly precautionary.

• With Tommy Pham still sidelined after a positive coronavirus test, Tingler said of the outfield race: "I don't know that we have any locked-down spots." But he mentioned Wil Myers and Trent Grisham as standouts in camp. They’re the clear favorites for starting roles in right and center field, respectively.

• Myers returned to his home in North Carolina during his time off. He built a home gym while also working out at a local hitting facility. He was asked Thursday about the possibility of serving as designated hitter, which seems unlikely given the Padres' abundance of other options there.

"My focus mainly is just being a great right fielder this year," Myers said.