U.S. co-captain Megan Rapinoe, who had scored all four of the Americans' goals in the knockout rounds, was on the bench Tuesday to start Team USA's Women's World Cup semifinal against England in Lyon.

No reason was given by coach Jill Ellis for Rapinoe not starting the win-or-go-home game, but Fox Sports reported at halftime that Rapinoe was out with a hamstring injury.

According to The Wall Street Journal, when asked whether the decision regarding Rapinoe was related to injury or if it was a disciplinary move, a U.S. Soccer spokesman said only that the decision was “not disciplinary.”

Forward Christen Press started in Rapinoe’s place and opened the scoring with a first-half goal.

“Christen Press will earn her 122nd career cap today and has scored 48 career goals and recorded 30 career assists. She also leads the USA in assists this year with seven. She is tied for 11th place on the all-time WNT goals list,” the USWNT announced before the game, making no mention of Rapinoe's benching.

A spokesman for the U.S. team told The Los Angles Times that he couldn't disclose the reason for Rapinoe's benching, unusual the Times noted in that when Becky Sauerbrunn and Julie Ertz did not start earlier in the 2019 World Cup the media were told why.

In Press' defense, she is considered among the fastest and fittest players on the U.S. side and offers a potentially better matchup against England's Lucy Bronze, who many consider the best player in the tournament thus far.

Barring an undisclosed injury or some other factor, Rapinoe, 33, could be used off the bench for offensive firepower. But reporters in Lyon noted Rapinoe did not even warm up with the rest of the team before the game.

Rapinoe at the bottom of the picture. No shin guards on, not warming up pic.twitter.com/INAJcqDX5m — Seth Vertelney (@svertelney) July 2, 2019

Rapinoe and Alex Morgan lead the U.S. scoring with five goals apiece. Carlie Lloyd has three and Samantha Mewis, Rose Lavelle and Lindsey Horan have two each.

The U.S.-England game kicked off at 3 p.m. ET.

The winner faces the winner of Wednesday's Netherlands-Sweden semifinal in Sunday's championship.

This story will be updated.