Tanner Roark won’t take the ball for the Nationals again for at least a week. (Toni L. Sandys/The Washington Post)

WEST PALM BEACH, Fla. — The Nationals expected to have Tanner Roark back by now. When he first committed to pitch for Team USA in the World Baseball Classic, the Nationals thought they might lose the righty for a week — one outing, tops. But now, they will be without their ace for at least two weeks.

The United States advanced to the second round of the tournament, and begins play Wednesday at 9 p.m. against Venezuela. Roark was in the U.S.’s designated pitcher pool, which meant the team could replace him with another designated pitcher before the second round. But after he allowed three runs in 1 1/3 innings of relief work Saturday night against the Dominican Republic, Roark chose to stay. Manager Dusty Baker was told Roark will pitch an inning on Wednesday night, then get a start later in the week.

While Oliver Perez and Jhonatan Solano returned after Mexico and Colombia were eliminated, Roark and Daniel Murphy remain away from Nationals camp for at least a few more days. Murphy played once, in the first game of the tournament for the United States, but has not been in the starting lineup since.

“You’d prefer [Roark] here, but he signed on for that, and you have to complete your obligation is the way I look at it,” Baker said. “I’d prefer Murphy back, too. He didn’t have his stuff together when he left. But like I said, when you sign up for something, you have to complete it, and while they’re there, they might as well try to win for the USA.”

Murphy was hitting .176 in six games before departing for the tournament, while Roark had appeared in two games and thrown seven scoreless innings. While A.J. Cole and Gio Gonzalez are working through their fourth starts of the spring, Roark will not have accumulated the same number of innings as they have — though he will have pitched in a more pressurized situation than any of his non-WBC teammates. Either way, the United States will be playing through at least Sunday, meaning Roark could return in time to get a couple more starts in before Opening Day, but giving the Nationals fewer than two weeks to get their rotation in order before the first week of the season.

If one could worry about Roark being under-worked early in the season, one could have opposite concerns about Perez, the crafty lefty who has been a part of Team Mexico for every World Baseball Classic. Perez played winter ball in Mexico, then played in the Caribbean Series before suiting up for Mexico in the WBC. All told, Perez threw 12 total innings for three different teams this winter, in addition to three innings for the Nationals so far this spring. He threw 40 innings for the Nationals in 2016.

“I know what I have to do and how I have to take care of myself,” Perez said. “When I have to rest, I rest. When I have to do something special, I do something. For me, I just have to take it easy and learn the process … I have to be ready every day, but when I need a day off, I have to take a day off.”

● Neither Perez nor fellow returnee Solano appeared in the Nationals’ 8-2 loss to the Astros on Wednesday, one that dropped their spring training record to 7-8. Righty A.J. Cole struggled against a lineup loaded with Houston regulars, allowing five runs and two homers — one of which bounced over the fence after hitting Bryce Harper’s outstretched glove.

Cole was supposed to go five innings in his fourth start of the spring, but could not escape the fourth inning, by which time he had walked three batters and struck out none. The bulked-up righty attributed some of the trouble to being too fine, but now has a 10.22 ERA in four spring starts.

● Lefty Sammy Solis relieved Cole, and allowed two hits in 1 1/3 innings. He is pitching to a 6.23 ERA this spring, and Baker admitted the lefty is allowing more hard contact than he and the Nationals are used to seeing.

“He’s healthy, which is our number one concern,” Baker said. “ … As long as Sammy is healthy, Sammy has his stuff. We want to make sure he gets his work in, gets his innings up so he can be ready to start the season.”

● Ryan Zimmerman got the first hit of what had been an 0-for-17 spring when he hit a chopper to deep third base in the second inning. Zimmerman finished the day with two hits, the second of which was a well-struck line drive to right center.

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