REIMS, France — Jill Ellis sat on the sideline and nibbled on her finger.

It was a sweltering Monday night, and her players on the United States women’s soccer team were deadlocked with Spain, one goal apiece, in their round-of-16 showdown at the Women’s World Cup. The clock had ticked into the 75th minute, and now Ellis’s captain, Megan Rapinoe, was preparing to take a penalty kick.

A lot hinged on the moment.

Spain is seen as the most rapidly ascendant national team in women’s soccer, embodying in many ways the global flow of power and, potentially, the future of the sport, as more of Europe’s traditional men’s soccer powers turn their attention to the women’s side of the game.

The United States is the traditional power of women’s soccer, a three-time winner of the World Cup, now watching the rest of the world rapidly narrow what once had been a sizable talent gap.

On the field Monday at the Stade Auguste-Delaune, Rapinoe took five short steps to the ball and drilled it into the lower left corner, scoring her second goal of the night from the penalty spot. Ellis leapt off the bench and embraced her assistant coaches as the crowd roared.