Hideki Matsuyama of Japan finished his second round, shooting 7-under 64, then shot 67 in the third round, and is one shot behind Xander Schauffele in the Olympic golf tournament. Matt York/Associated Press

KAWAGOE, Japan — Just over three weeks ago, Hideki Matsuyama was in isolation for COVID-19 and desperate to record a negative test to have any chance of competing in his home Olympics.

Even when he cleared that hurdle, it was a matter of building endurance for stifling heat and shedding rust from not having played a full tournament since the U.S. Open six weeks ago.

And on Sunday, he steps onto the tee in the final group, one shot behind Xander Schauffele, a gold medal within his reach for a country with high hopes for its Masters champion.

“I definitely could not have believed it,” Matsuyama said after a full Saturday that began with him capping off a 7-under 64 in the rain-delayed second round and then posting a 67.

“To be honest, the endurance part of my game has been struggling a little bit,” he said. “Thankfully, it’s held up the last few days. Hopefully, it’s going to hold up tomorrow, as well.”

Adding to the test was a medal round at Kasumigaseki Country Club that was wide open.

Schauffele, the 27-year-old American whose mother was raised in Japan, didn’t have a lot go his way Saturday until he finished on a strong note, firing a 9-iron to within 3 feet for a birdie and a 68 to keep his one-shot lead.

So wild was the third round that five players had a share of the lead at one point and there was a three-way tie among Schauffele, Matsuyama and Carlos Ortiz of Mexico going down the 18th when the American made birdie.

That left Schauffele 18 holes away from an Olympic gold medal, and the podium still felt like it was miles away.

He was at 14-under 199.

BASEBALL: Nick Martínez stepped onto the mound, and it felt like an old familiar place.

Because it was.

“Felt comfortable the whole game,” he said after striking out nine over five innings and pitching the United States over South Korea 4-2 for a 2-0 record at the Olympics.

A right-hander who turns 31 on Thursday, Martínez (1-0) allowed one run and four hits.

He was 17-30 for Texas from 2014-17 and signed with the Pacific League’s Hokkaido Nippon-Ham Fighters after the Rangers demoted him to Triple-A 13 times. He switched to the Fukuoka SoftBank Hawks this season and is 7-2 with a 2.03 ERA.

While Major League Baseball refused to allow 40-man roster players at the Olympics and many teams blocked top prospects from participating, Nippon Professional Baseball stopped its season, as did the Korean league (KPO).

“I’m familiar with Asian-style baseball,” Martínez said. “I’ve been fortunate to watch a little bit of the KBO during quarantine last year, so I was able to see some of these guys play and get some information on them. And playing at this field definitely helps.”

Scott McGough, Edwin Jackson, Anthony Gose and David Robertson finished a five-hitter for the Americans, who struck out 14.

Red Sox prospect Triston Casas hit a go-ahead, two-run homer in the fourth off side-arming right-hander Ko Youngpyo (0-1), and Nick Allen went deep with a solo shot in the fifth.

WOMEN’S TENNIS: A Swiss tennis player won gold in singles at the Olympics and it’s not Roger Federer or Stan Wawrinka.

Belinda Bencic accomplished something Saturday that her better-known fellow Swiss players never managed.

And she’s not done yet.

The 12th-ranked Bencic beat Marketa Vondrousova of the Czech Republic 7-5, 2-6, 6-3 at the Tokyo Games for the first major title of her career and she’ll also contest the women’s doubles gold medal match on Sunday.

Bencic and Swiss partner Viktorija Golubic face the top-seeded Czech team of Barbora Krejcikova and Katerina Siniakova.

“It’s unbelievable to have two medals, to have one gold and the other still to be decided,” Bencic said. “I will give all the energy that I have left in me.”

Federer and Wawrinka won gold together in men’s doubles in 2008 then Federer lost the 2012 singles final to Andy Murray at Wimbledon.

Not even Martina Hingis, the Swiss player who Bencic’s career was inspired after, claimed an Olympic title. Her best result was silver in women’s doubles in 2016 with Timea Bacsinszky.

TRACK AND FIELD: The American lineup for the 1,600-meter mixed relay was rather unexpected — no Allyson Felix.

The color of Olympic medal, too – bronze.

Given their whirlwind of emotions – disqualification in the opening round for an exchange, appeal, late-night reinstatement into the final — any medal was cause for celebration.

The United States wound up behind gold medal-winning Poland and runner-up Dominican Republic as the mixed relay made its Olympic debut Saturday night at the Tokyo Games.

From start of the event to the finish, it was a wild ride for the Americans.

“We had to keep the faith,” anchor leg Vernon Norwood said. “We all feel kind of satisfied, walking away having a chance to compete. That was the thing we were looking forward to most. We ended up getting our joy back and ended up with some hardware.”

The U.S. was disqualified for a bad exchange in the opening round Friday. The Dominican Republic also had been disqualified. Both were reinstated hours after the race.

On Saturday, no one could catch Poland. The real race was for second, with Alexander Ogando falling over the line to give the Dominicans the silver by .01 seconds.

There was some thought Felix might be on the track for the final with a chance to win her record 10th Olympic medal. It will have to wait.

She combined with Wil London, Courtney Okolo and Michael Cherry to take home gold when the event made its major meet debut at the 2019 world championships in Doha.

MEN’S SOCCER: Mikel Oyarzabal helped Spain into a second semifinal in a month. Brazil remains on track for a quick return to another final.

With youthful squads, Olympic men’s soccer lacks the status of the European Championship or Copa America. The Tokyo Games still offer the chance for the countries to collect trophies this year.

The Spanish were taken by Ivory Coast to extra time before winning 5-2 on with Rafa Mir scoring a hat trick and the go-ahead goal from a penalty by Oyarzabal, who also netted the winning spotkick in a shootout in the Euro 2020 quarterfinals. The continental semifinal was lost to Italy. Now a more youthful Spain squad will be hoping to find a way past Japan, which was taken to penalties by New Zealand before winning the shootout 4-2.

The gold medalist on home soil in 2016, Brazil continued its title defense with a 1-0 victory over Egypt secured by Matheus Cunha’s low strike in the 37th minute in Saitama.

The goal was set up by Richarlison, who has been allowed by Premier League club Everton to do double duty in the offseason, having already been in the side that lost to Argentina in the Copa America final three weeks ago.

Egypt wasn’t allowed to bring players from England’s top league like Brazil – particularly Liverpool striker Mohamed Salah as one of the three players over the age of 24 permitted in the men’s competition.

WOMEN’S RUGBY 7s: After five long years, Portia Woodman has finally been able to shake the mental image of herself in tears, standing under the goalposts.

It was like grief for something lost, but it’s been supplanted now by memories of happiness, hugs and, of course, a haka.

Woodman’s New Zealanders won a coveted Olympic title by beating France 26-12.

She’ll always have the memory of that 2016 final loss to Australia in Rio de Janeiro, because missing out on the first Olympic gold medal ever awarded in women’s rugby sevens was the motivating force for everything that has come since.