TOKYO — Jordan Thompson kept trying, kept testing, kept pushing. She had leapt at the net and landed on a teammates' foot, rolling her ankle. She had sat on the ground, breathing rapidly, cradling her foot, and, minutes later, she was trying to walk on the sideline, pain and frustration etched on her face.

She limped. She tested the range of motion in her ankle by trying to do toe raises. She seemed to be trying to talk her way back into the match.

Thompson then sat on the bench, ankle raised, and a trainer packed ice on the injury before she finally walked out of the arena, limping, one arm around a trainer's shoulders.

Thompson, of Edina, is the star outside hitter on the the U.S. women's volleyball team. She played collegiately at Cincinnati and has become a star during these Olympics.

The Americans entered their match with the Russian Olympic Committee on Saturday in Toyko with a 3-0 record. ROC was 2-1.

ROC won in three sets, 25-20, 25-12 and 25-19. The U.S. and ROC are tied for second in pool play behind unbeaten Italy. The U.S. plays Italy on Monday. The top four teams in each pool advance to the quarterfinals.

The U.S. will advance, but can the Americans contend for gold if Thompson is injured or limited?

"She's done a really nice job in this tournament so far," Team USA coach Karch Kiraly said. "We're hoping to get her back. The word I got during the match was, it's not a major ankle sprain. Something below that, somewhere between mild and medium.

"We will learn more when they do what is standard — take an X-ray and an MRI. I was told we can be somewhat hopeful that she can be back in action in a few days.

"Again, I don't know what that means. I would think that means she's unlikely for Italy and maybe hopeful for something beyond that. I'll know a lot more by the end of today and the first thing tomorrow. It's also important to see how treatments go and how they feel the first thing (Sunday)."

The quarterfinals begin Wednesday. If Thompson doesn't play against Italy on Monday, she would have four full days in which to recover.

The combination of a noncompetitive loss to ROC and Thompson's injury created the first doubtful moment of the Olympics for the U.S. women's team.

The Americans are ranked first in the world but they haven't won gold in 57 years. They were upset in the semifinals in Rio in 2016 and settled for bronze.

Kiraly is a volleyball legend known for his even temper. He did not sound any alarms after the loss to ROC. But he praised the Russians' play and admitted that the U.S. didn't assert itself enough on offense to offset their powerhouse hitting.

"You've got to give Russia a ton of credit," he said. "They just played a really sharp, really clean game of volleyball ... Our sideout game got really disrupted and broken down today by the Russian serving, by their block and by their defense.''

ROC won the first set even when Thompson was healthy, but U.S. captain Jordan Larson said, "It's certainly emotional. We love Jordan and she's had a really good tournament so far. We're wishing her well and hope to find out more soon.

"It's definitely hard when anybody goes down. It shifts the energy a bit and we had to work hard to overcome it, and didn't really do that.''

Kiraly sounded optimistic about Thompson. He's probably going to need her if the U.S. women are going to break the drought and win a gold.