Washington Nationals left-hander Jon Lester is leaving spring training camp to have surgery for the removal of his thyroid gland, manager Dave Martinez said Wednesday.

The 37-year-old Lester was to travel from West Palm Beach, Florida, to New York on Wednesday; the Nationals said the operation is planned for Friday.

“Hopefully he can pitch again in about a week,” Martinez said in a video conference with reporters before Washington’s exhibition game against the Miami Marlins. “We want him to get it taken care of now, so it’s not an issue.”

Martinez said the Nationals “still have plans, as of right now, that he will start the season with us on his scheduled day, but we’ll have to see — after this procedure’s done — how he’s feeling.”

In 2006, Lester’s rookie season with the Boston Red Sox ended early because he was diagnosed with a form of lymphoma.

He underwent chemotherapy treatments and returned to the Red Sox at spring training before the following season.

Lester is entering his 16th year in the majors and first with Washington. He was a free agent and joined the Nationals on a $5 million, one-year contract after playing the past six seasons with the Chicago Cubs.

The starting pitcher originally was scheduled to make his first appearance for Washington in a Grapefruit League game Thursday.

But Martinez said that after additional test results came in, a decision was made Tuesday for Lester to have the surgery.

He said Lester had been feeling tired.

“That’s the big issue. I feel like once they get this out, he’ll have a lot more energy throughout the day,” the manager said. “I hope it works out for him. I really do. He’s a big part of what we do here and we love having him. He’s been working his tail off, day in and day out, and I know he’s going to help us.”

Washington added Lester to a star-studded rotation that already included three-time Cy Young Award winner Max Scherzer, 2019 World Series MVP Stephen Strasburg and lefty Patrick Corbin.

NOTES: RF Juan Soto was in Wednesday’s lineup for his exhibition debut, hitting No. 2, behind CF Victor Robles and ahead of SS Trea Turner. ... Martinez said the team will use a series of relievers Thursday.

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