TOKYO — During the baseball season, Tyler Austin plays his home games at Yokohama Baseball Stadium as part of the Yokohama DeNA Baystars, a team in Japan’s top professional league.

And now, on the U.S. baseball team at the Olympics, that very stadium is also home for Austin.

That familiarity — with not only his surroundings but the opposing pitchers as well — has helped Austin, 29, a former Yankees prospect, power the United States to the gold medal game on Saturday night. The opponent: Japan, a team made up of the very same players Austin faces in the professional league the rest of the year.

The experience has served him well. Through five games in the tournament, Austin, a designated hitter, is batting a team best .429 (9 for 21) with two home runs and seven runs batted in.

With the Baystars this year, Austin’s second with the team, he is enjoying an even better season than last. He is hitting .314 with 19 home runs and 49 R.B.I. through 68 games. He credited his wife with crafting an off-season workout and nutrition plan that he said had helped him gain strength after he lost too much weight last year.

Because the Nippon Professional Baseball league, unlike Major League Baseball, takes an Olympic break, Austin was able to play for the United States. But it’s also why Japan is the favorite to claim its first Olympic gold medal in baseball and is the only undefeated team in the tournament.

“These are definitely the best arms they’ve got over here,” Austin said of Japan’s pitching staff.

Given that most of his teammates had never faced most of Japan’s arms entering the Olympics, Austin has tried to serve as a resource to them beyond simply video. “Any little information that I can give — I try to do my best to give the best scouting report that I can,” he said.

He might be helping: As a whole, the United States is hitting .247 — trailing South Korea (.294) and Japan (.288) — but leads in slugging percentage (.434) entering Saturday. (The United States’ strength has been its pitching: Its collective 2.18 earned run average is more than a whole run better than the next best team.)

Austin will have to serve as an advance scout for his teammates again heading into the gold medal game: Japan will start Masato Morishita, the 23-year-old right-hander who is one of the best talents in N.P.B. on the Hiroshima Toyo Carp. In a 7-4 win over Mexico earlier in the tournament, Morishita allowed two runs over five innings and struck out three batters.

“I’ve faced Morishita a few times,” Austin said. “Hopefully I can give a pretty good scouting report on Saturday.”