Nationals’ pitcher Ross Detwiler has already played a crucial role in an important first-round World Baseball Classic game. He called the experience unforgettable (Charlie Riedel/AP)

Gio Gonzalez climbed the mound at Marlins Park here in his home town Tuesday night, the large block letters of USA spread across his chest. In the Americans’ second-round opener of the World Baseball Classic, Gonzalez tormented Puerto Rico’s hitters with his electric fastball and biting curveball.

On the top step of the dugout was Ross Detwiler, his Washington Nationals teammate who helped pitch Team USA to this point.

Both players considered it a once-in-a-lifetime honor to represent their country, and immediately pounced at the opportunity when asked. While other players fear injury playing in the international tournament, Detwiler and Gonzalez were willing to leave their team, considered contenders for the World Series, to wear the same red, white and blue uniforms as some of their major league rivals. And to hear them talk, they don’t regret the decision.

“It’s been incredible,” Detwiler said. “It’s a dream come true to play for your country.”

In what is essentially only his fourth start of spring training, Gonzalez appeared to be in midseason form in the South Florida humidity, firing five scoreless innings in a 7-1 U.S. win and striking out five. The native of nearby Hialeah used a trick from Team USA pitching coach Greg Maddux to contain his nerves as he baffled Puerto Rico. He threw only 69 pitches, well under the 80-pitch limit for this round. His friends and family, as well as those of Detwiler, were among the crowd of 32,872.

When Detwiler took the mound on Saturday in the sixth inning against Italy with a 6-2 lead, he fought to contain his emotions. He tossed four scoreless innings and notched his first save. He was awarded the game ball, which he had authenticated and will hang in a place of honor in his home.

“At the end, you look up and you’re like, now you let it hit you . . . and it’s like, ‘We were just competing against another nation,’” Detwiler said. “It’s pretty cool.”

Detwiler said it has been “awesome” working with pitching legend Maddux. He has gotten to know some players he knew only from competing against them in games as Nationals opponents. Gonzalez said Maddux told him tune of the pressure of the situation by focusing on a small routine task like fishing or fielding a ground ball.

“From the experience in the postseason, I was overwhelmed by all the noise and stuff like that,” Gonzalez said. “But I look at it now and I try to do the same thing. What Greg did, take that away and try to minimize it.”

Detwiler said he felt as if he has been away from the Nationals for a long time even though it’s been less than two weeks. He has kept up with the Nationals through the news. He was sad to miss two off days that he could have spent with his teammates. (“It’s kinda hard to cheer on your team from a computer screen.”) He took up golf this year because he wanted to play in Monday’s annual spring training par-3 golf tournament with his teammates. “And I miss it,” he said.

But there is no regret in Detwiler’s voice. His American teammates on the Nationals have flooded him with text messages of good luck. The experience has taken a different feel for him and Craig Stammen, who both went on a USO tour to visit troops in the Persian Gulf and Afghanistan. “It kinda makes it a little more special getting over there and being able to meet all those guys,” Detwiler said.

While critics may view the event simply as glorified exhibition, the players are taking it quite seriously. Watching the United States come back in a must-win game over Canada on Sunday, Detwiler said, was “like a playoff game.” The game between Mexico and Canada was halted by a brawl between two fiery teams.

“You can’t tell me they didn’t take it seriously,” Detwiler said, referring to the melee Saturday in Phoenix. “Everybody’s taking it seriously. Everybody’s out here to win. Nobody’s out here just to show up. There’s a lot of pride at stake. You get back to your team and you’re playing with a lot of the guys you compete against in spring training and you want to be able to go back there and say you won it.”

Unlike Detwiler, Gonzalez wasn’t going to join the U.S. team unless it advanced to the second round. Gonzalez doesn’t throw much during the winter, so the Nationals wanted him to get three starts with them in spring training.

Gonzalez was so confident the United States would advance that after throwing a bullpen session Sunday morning in Viera, Fla., he made the three-hour drive home to Hialeah to watch the game against Canada. Even when the United States trailed 3-2 in the seventh inning he was confident.

“I was in Flanagan’s in Hialeah watching this game, and I was just going nuts, just having some chicken wings and some water,” Gonzalez told reporters during a Monday news conference. “Other than that, I was ready to go. I was ready to watch these guys compete and play at the top of their performance. When [Eric] Hosmer came up with the big hit clearing the bases [in the ninth], that was it. That’s a big deal for me.”