By Mike Dougherty

PHILADELPHIA (CBS) — The U.S. Women’s Field Hockey team continues its march toward an Olympic gold medal tonight in Rio with a game against Great Britain. A sports psychologist from Philadelphia is helping keep their minds sharp.

The U.S. women are 4-0, outscoring their opponents by a total of 11-3 in those games.

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Yogi Berra famously said “baseball is 90-percent mental. The other half is physical.”

The same goes for field hockey, according to sports psychologist Dr. Joel Fish. He says nearly every game between the lines is won and lost between the ears.

“The whole goal though is to get the mind ready to perform on the big moment when the spotlight comes on,” Fish said. “In the same way that athletes have prepared themselves physically, they prepare themselves mentally, so that when the light comes on and it’s their time, they’re able to say to themselves, ‘I’m in this situation. I know what to do.'”

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Thirteen of the 16 players on Team USA are from Pennsylvania, New Jersey and Delaware, including team captain Lauren Crandall of Doylestown and leading scorer Katie Bam from Blue Bell, who scored a hat trick in a 6-1 victory over Japan.

“They’re advancing to the quarter finals,” Fish said. “They’re exceeding expectations at this point, and I think if they stick to the physical and mental game plan, great things can happen.”

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USA and Great Britain face off Saturday at 5 p.m.