Sauerbrunn took to social media on Friday night, saying: “Heartbroken isn't even the half of it.”

“I had hoped and worked and hoped some more to make it back in time to help lead the team at this World Cup, but after lots of discussion, unfortunately, there's just too much variability in my return to play timeline,” she wrote. "So, I'll be home, working as hard as I can to get back on the field as quickly as I can.”

The U.S. women's national team is expected to unveil its 23-player roster for the World Cup next week. The two-time defending World Cup champions will play a send-off match against Wales in San Jose on July 9 before departing for the tournament, co-hosted by Australia and New Zealand.

The United States, winner of four World Cups overall, opens the World Cup with a match against Vietnam on July 22 in Auckland.

The loss of Sauerbrunn is a blow to the team. The 38-year-old defender is considered among the top players in the world at center back and anchored the backline for the World Cup champions in 2015 and 2019.

Sauerbrunn, who plays professionally for the Portland Thorns in the National Women's Soccer League, originally hurt her foot in April. She briefly was a substitute in a June 3 match against the Reign, but hasn't played since. The nature of the injury has not been made public.

Sauerbrunn has played for the senior national team since 2008, appearing in three total World Cups. She also won a gold medal at the 2012 London Olympics and a bronze at the Tokyo Games in 2021.

“It's been an honor to work and play alongside this incredible group of athletes,” Sauerbrunn wrote. “They have my unwavering support. And, more importantly, they have my unyielding belief. This program has always been about the collective and I have no doubt that the twenty-three players on the final roster have everything they need — in their feet, their heads and their hearts — to bring our fifth trophy home.”

The United States has been hit with injuries ahead of the World Cup. Forward Mallory Swanson had surgery after injuring her left knee during an April exhibition match against Ireland. Fellow forward Catarina Macario recently announced that she would miss the World Cup after tearing her ACL playing for her club team in France last year.