Ariarne Titmus of Australia rests after winning the final of the women’s 400-meter freestyle at the 2020 Summer Olympics on Monday in Tokyo. (AP photo)

TOKYO — Ariarne Titmus and Luka Doncic made memorable Olympic debuts.

Titmus lived up to the billing of her nickname the “Terminator” when she chased down Katie Ledecky in the 400 freestyle Monday to win one of the most anticipated races of the Summer Games.

Doncic scored 48 points in his first Olympic appearance to tie for the second most ever in men’s basketball history, leading Slovenia to a 118-100 victory over Argentina.

Titmus trailed by nearly a full body-length at the halfway mark of the eight-lap race before erasing the gap and finishing in 3 minutes, 56.69 seconds. It was the second-fastest time in history, surpassed only by Ledecky’s world record of 3:56.46 from the 2016 Rio Games.

“It’s probably the biggest thing you could pull off in your sporting career,” Titmus said, “so I’m over the moon.”

Ariarne Titmus of Australia poses with the gold medal after winning the final iin the women's swimming 400-meter freestyle at the 2020 Summer Olympics on Monday in Tokyo. (AP photo)

Ledecky lost an individual Olympic final for the first time after winning the 800 free at the 2012 London Games, then capturing three more golds in the 200, 400 and 800 free at Rio de Janeiro five years ago.

Doncic scored 31 points in the first half, putting him on pace to break the Games’ scoring record of 55 points by Brazilian Hall of Famer Oscar Schmidt in 1988. He ended up tied with Eddie Palubinskas, who had 48 for Australia in the 1976 Games in Montreal.

“I don’t care about records,” he said. “We got a win and that’s what we came here for.”

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QUEST FOR SIX

Caeleb Dressel started his quest for six gold medals in swimming by leading the United States to victory in the men’s 4×100-meter freestyle relay.

Dressel, who has been hailed as the successor to Michael Phelps, gave the U.S. the lead in the opening leg and his teammates made sure it stood up.

“I felt good the whole way, I knew I had to get my hand in the wall first and get some clean water,” Dressel said. “And everyone did their job. It’s a relay for a reason, it’s four guys for a reason, it’s certainly not just me. It’s certainly not just one guy.”

Dressel is competing in three individual events and two more relays in Tokyo.

The other winners in the pool on Monday were Britain’s Adam Peaty in the men’s 100-meter breaststroke, Canada’s Maggie MacNeil in the women’s 100-meter butterfly.

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GYMNASTICS GOLD

Nikita Nagornyy nailed his floor routine with the entire gym watching, and the Russian men completed their long climb back to the top of the gymnastics world by edging Japan and China in the team final.

It’s the first Olympic title for the Russians since the 1996 Atlanta Games.

Nagornyy needed a score of 14.564 to deliver gold, and the reigning world champion came through with a 14.600.

The team representing the Russian Olympic Committee finished with 262.500 points, just good enough to hold off the sport’s other two superpowers. Japan used a brilliant high bar routine by Daiki Hashimoto in the final rotation to surge past China for second with a score of 262.397.

The Chinese were undone by a fall from Lin Chaopan on floor exercise during the first rotation.

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TUNING UP

A dramatic comeback for the U.S. softball team against Japan earned the Americans a small prize. When the countries play again it will be for the gold medal.

Kelsey Stewart homered leading off the seventh inning to lead the U.S. to a 2-1 victory to win the group stage and give it the right to bat last in the gold medal game. The longball was the first for the United States this tournament.

“It’s like you dream about when you’re a little kid, about hitting a home run at the Olympics, let alone a walkoff,” Stewart said.

Monica Abbott pitched a perfect seventh in relief for her third win of the tournament. She is likely to start Tuesday’s gold medal game, a day before her 36th birthday.

The Americans lost the gold medal game 3-1 to Japan in 2008, the previous time softball was in the Olympics.

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TEEN SPIRIT

Youth was served at the debut of the Olympic skateboarding event for women.

Three teenagers swept the podium at the street event with 13-year-old Momiji Nishiya of Japan taking the gold medal, 13-year-old Rayssa Leal of Brazil getting silver and 16-year-old Funa Nakayama of Japan winning bronze.

Both Nishiya and Leal became their countries’ youngest ever medalists.