TAMPA, Fla. — Dellin Betances knew all winter he’d be departing Yankees camp early for the World Baseball Classic, and he prepared accordingly.

The reliever did extra work in the offseason. He spent a full month in the Dominican Republic working out at Fausto Mejia’s baseball academy, compared to the 2 ½ to three weeks he typically spends there, to “speed up the process” of being game-ready.

Betances has been sharp in live batting practice sessions and in a simulated game, and in his exhibition debut Wednesday night against the Braves, Betances continued to look impressive. Though often out of the strike zone, the righthander did not allow a hit and struck out one in a scoreless inning. Betances threw 20 pitches (10 strikes) and walked one, DH Matt Kemp.

“Breaking ball was good, fastball was good early,” Betances said. “The only bad thing I felt was Matt Kemp, I started pulling a little bit, but then I gathered myself.”

Before the game, Joe Girardi said that while watching Betances throw a simulated game six days earlier, he thought he “was in midseason form.”

“His BPs, the simulated game, they’ve been fabulous,” Girardi said.

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After Bryan Mitchell threw three scoreless innings, Betances came on for the fourth. He got ahead of Brandon Phillips 0-and-2, eventually getting him to pound a curveball to third for a routine 5-3 play. Betances got Jace Peterson to ground softly to second, walked Kemp, then struck out Tyler Flowers swinging at a curveball, the pitch he’s been most pleased with this spring.

The Yankees held on for an 8-7 win after taking an 8-0 lead.

Betances will pitch Saturday in Lakeland against the Tigers before leaving Sunday for Bradenton, where he’ll spend a couple of days with the Dominican Republic’s loaded WBC team. Robinson Cano, Manny Machado, Adrian Beltre and Jose Bautista are just a handful of the stars on the roster, which will be managed by Yankees bench coach Tony Pena. The team will head to Miami for pool play, which begins March 9.

Betances made headlines earlier in camp for off-the-field news. He lost his arbitration hearing — he’ll make $3 million this season instead of the $5 million he asked for — and soon found himself in a war of words with team president Randy Levine.

The reliever described himself as angry but also expressed his wish to focus on the rest of spring training and the WBC and getting ready for the regular season. Girardi said he talked to Betances after the arbitration spat and had no worries about the pitcher moving on.

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“I really didn’t have much concern about it because I really think when Dellin gets out here, he’s Dellin,’’ Girardi said. “It’s (arbitration) an uncomfortable situation for everyone involved. It will pass. Competition starts and Dellin will be Dellin and that’s all you worry about.”