TOKYO (AP) — Chase Kalisz knows what’s coming: Pain, and lots of it in the 400-meter individual medley that gets swimming underway at the Tokyo Olympics.

The eight-lap race requires endurance, technique and strategy while fighting off weary legs and arms churning through all four strokes — butterfly, backstroke, breaststroke and freestyle — not to mention negotiating the many turns.

“I’ve had races where I was never really nervous for the race but I was more so nervous for the pain that was about to come and how I was going to feel the next day,” Kalisz said. “That’s really what the culmination of this year for me has been, embracing that, looking forward to that.”

The nine-day competition begins Saturday night with preliminary heats in six events. Four finals will be contested on Sunday morning, the first time finals are held in the morning since the 2008 Beijing Games so they can be shown live in prime time in the U.S.

Besides the early start, they’ll walk to the starting blocks without fans in the 15,000 seats at the Tokyo Aquatics Centre because of the coronavirus pandemic.

“I love the crowd, I love the noise, I love having packed arenas,” Kalisz said, “but swimming is a pretty solo sport. We spend most of our time in isolation by ourselves. I don’t think it’s going to be a big factor.”

Five years ago in Rio, Kalisz was leading the 400 IM when Japan’s Kosuke Hagino caught up on the freestyle leg and pulled away over the final 25 meters.

The grueling event made its Olympic debut at the 1964 Tokyo Games. American swimmers have claimed gold eight times in the previous 14 editions.

Kalisz and Daiya Seto will be seeking to upgrade the medals they earned in Rio. Kalisz settled for silver and Seto took bronze. Seto is a three-time world champion in the event.

“There’s not too many left of those for me,” Kalisz said, “so I’m going to make every single one of them hurt as much as I can. I’m looking forward to it.”

Katinka Hosszu of Hungary goes for a second straight gold medal in the women’s 400 IM. The 32-year-old could become the second-oldest woman to win a swimming gold medal at the Olympics if she can defend her title.

Elijah Winnington of Australia comes into the men’s 400 freestyle with the fastest qualifying time. He’ll be challenged by Gabriele Detti of Italy, who’ll try to end the Aussies’ dominance in the event. They’ve won it six times.

The women’s 4×100 free relay shapes up as Australia vs. the U.S. The Aussies have won it in three of the past four Olympics; the Americans haven’t won since 2000.

U.S. stars Caeleb Dressel and Katie Ledecky and an Australian team led by Kaylee McKeown, Ariarne Titmus and Kyle Chalmers figure to help their countries pile up the most medals at the pool.

The Americans won 33 medals, including 16 gold, in Rio. Australia claimed 10, and three golds. Japan earned seven medals — two golds — five years ago, but should get a boost as the host nation.

The Americans have topped the medals table in swimming at every Olympics since Seoul in 1988. The Aussies moved their trials to six weeks before the Games, roughly at the same time as the U.S., rather than the previous six-month gap.

“The Americans have historically proved at the Olympic Games that they perform, so for us they are the standard we are striving for,” Australian coach Rohan Taylor said. “We haven’t performed to our potential (at the last two Games) and our decision to shift the timing of our trials was to find a better way to cover our performances at the Olympics.”