David Wright had his cleats tied, his uniform on and tucked in, and three big letters, USA, across his chest. He was ready to go, to play his figurative Captain America role at the World Baseball Classic and continue some of what he had called the best times of his baseball life.

Then, minutes before the American team was set to play the Dominican Republic on Thursday night for a spot in the semifinals, word spread: Wright was scratched from the lineup with what was called a sore back.

Just before the game, in a television interview, Ryan Braun said it would be hard to go on without Wright, but he hoped the United States had “a team full of superheroes,” and that another would step up.

Of course, in front of these fans Thursday, the Americans were the villains. Or so it seemed when Nelson Cruz crossed home plate in the ninth inning to score what proved to be the winning run. When he yanked the front of his jersey, which read Dominicana, the noise from the crowd was nearly deafening.

The Dominican players poured from the dugout, as if the crowd’s roar had pushed them out, and the celebration carried on into the night as the Dominican Republic won, 3-1, to clinch a spot in the W.B.C. semifinals alongside Japan and the Netherlands.

“First, I thank God,” the Dominican manager, Tony Pena, said in Spanish while tearing up at his postgame news conference.