Chase Kalisz wins 400-meter individual medley for first U.S. medal in Tokyo

gold at the Olympic pool.

Six of them in all, quite a start Sunday for the Americans in the post-Michael Phelps era.

off," said Kalisz, who won the 400-meter individual medley.

In Phelps record-setting career, which encompassed five Summer Games, they never won six medals in the first session of finals.

The Aussies, who hope to challenge America's dominance in the pool, picked up three medals Sunday.

medal winner of the Tokyo Games, and Jay Litherland - who was born in Osaka - made it a 1-2 finish for the Americans by rallying on the freestyle leg to claim the silver.

"I was surprised with myself," said Hafnaoui, who joined Ous Mellouli as a gold medalist from the north African country.

"After we saw [Kalisz and Litherland go 1-2], we kind of looked at each other and said, 'It's our turn,'" Weyant said.

"To come back and do this with Chase means a lot," said Litherland, who finished fifth in the 400 IM at Rio.

After putting on their medals during a masked-up victory ceremony, Kalisz and Litherland walked around the deck arm-in-arm.

That was the same format used at the 2008 Beijing Games, where Phelps won a record eight gold medals.

He retired after Rio, having captured 23 gold medals overall, but the Americans still have plenty of star power for the post-Phelps era.