WEST PALM BEACH, Fla. — Miguel Castro passed his biggest test of the spring Sunday, increasing his chances of beginning the season in a prominent Mets bullpen role.

After Jacob deGrom recorded two outs in the fifth, manager Luis Rojas summoned Castro to face the Nationals’ best hitter, Juan Soto. The right-hander struck out Soto to conclude the inning. It was the only batter Castro faced.

“We want to have guys come in during the middle of an inning, so it doesn’t happen for the first time when we are in the regular season, so it was preset to be like that,” Rojas said after the Mets’ 6-2 victory at The Ballpark of the Palm Beaches.

In his five appearances this spring spanning 4 ¹/₃ innings, Castro still hasn’t allowed a hit. The Mets acquired Castro last year at the trade deadline and watched him struggle with his control.

“You think of the different situations in which he can come in,” Rojas said. “When he got a test like today to enter in the middle of the inning, I know it was bases empty, but to face Juan Soto at any spot of the game, that is a lot of stress. He came in and threw some nasty pitches there.”

Dellin Betances pitched a scoreless seventh inning in which he impressed Rojas in breaking off the mound to cover first base. The right-hander tore an Achilles in 2019 that has affected his mobility.

The Mets’ projected Opening Day lineup started, with the exception of James McCann. Rojas indicated he held out McCann so he could work with Joey Lucchesi for the first time in Monday’s game. Tomas Nido started behind the plate for deGrom.

Arodys Vizcaino, who is competing for a bullpen job, has received treatment in recent days for elbow discomfort. The right-hander is expected to be available by the weekend. Another reliever, Drew Smith, has shoulder soreness and there is less clarity when he might resume.