TAMPA, Fla. — Yankees shortstop Didi Gregorius will miss at least the first month of the season with a shoulder injury suffered playing second base in the World Baseball Classic.

The Yankees have been bracing for bad news about Gregorius since Sunday, when they learned about the injury in his throwing shoulder. Gregorius returned to the Yankees on Monday and underwent tests Tuesday, including a dye-contrast MRI. The tests confirmed a strain of the subscapularis, a large triangular muscle in the shoulder.

An MRI taken Sunday also showed a hematoma, which is defined “as a solid swelling of clotted blood within the tissues.”

Gregorius will be shut down for two weeks before beginning a throwing program. The Yankees open the season April 2 at Tampa Bay.

“It’s not what I wanted to hear,” Gregorius said. “Not good news.”

General manager Brian Cashman said he hoped Gregorius would return in six weeks, but added that was just a “guesstimate.”

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“From what I was told (by the doctors), two weeks of doing no throwing at all, which allows some of the healing process to go through,” Cashman said. “And then they’ll get him going and probably a light throwing program and then progressing from there. But I was told basically we’re shooting for probably six weeks total. Maybe it’s sooner or maybe it’s later.”

Cashman mentioned five possible fill-ins for Gregorius: utilityman Ronald Torreyes, who started Tuesday night’s exhibition game against the Red Sox; non-roster players Ruben Tejada and Pete Kozma; prospect Tyler Wade, who never has played above Double-A, and second baseman Starlin Castro, who could slide over to his original position. But if Castro switched, that would create an opening at second.

“We’ve got (less than) two weeks to crash-course it and really drill down on who out of this crew that we should focus on,” Cashman said.

Cashman ruled out 20-year-old super prospect Gleyber Torres, who is batting .464 in spring training but never has played above Class A.

“Gleyber Torres will not be considered for that position despite how great he has looked,” Cashman said. “Gleyber’s time, I think, is coming at some point. And whenever that’s going to be, it’s going to be. But it doesn’t have to be right now.”

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Gregorius said he was injured making a throw to complete a double play for the Netherlands in an exhibition game Saturday against the Diamondbacks. Gregorius getting hurt while playing out of position in the WBC once again has raised the issue of the risk to teams of sending their players to the international tournament.

The Yankees, for example, lost Mark Teixeira to a wrist injury for most of the 2013 season, the last time the WBC was held. Teixeira was injured during WBC batting practice. The original estimate was he would be out 2-4 weeks. He played in 15 games that season.

While Cashman said the WBC and the risk of injuries is a fact of life all teams have accepted, manager Joe Girardi was less generous.

“Those are some of the concerns you have when players go to the WBC,” Girardi said. “We always worry about the injury factor. I know it’s important to the game, but he’s really important to our team.”

Gregorius, who played six tournament games for the Netherlands plus exhibition games, said he doesn’t blame the WBC.

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“It could have happened anywhere,” he said. “So it’s not like, ‘Oh, because I went to WBC it happened.’ So it’s not because of that.”