(CNN)Arms aloft and waving his finger, Michael Phelps left nobody in doubt just who was No. 1 Tuesday.

The world's most successful Olympian took his remarkable record to 21 gold medals on a stunning night for the United States in the pool.

While Phelps won the 200-meter butterfly and the US team took gold in the 4x200 meter freestyle relay, Katie Ledecky claimed her second title of the Games.Both Phelps and Ledecky have dominated in the pool but it was the main man who commanded the attention after exorcising his demons of yesteryear.

Four years on since losing his 200-meter Olympic butterfly title, Phelps taught his rival Chad le Clos a brutal lesson.

The oldest individual gold medalist in Olympic swimming history at 31, Phelps celebrated by hugging baby son Boomer after taking in the adulation of a raucous crowd.For Phelps, who quit the sport after London 2012 and then returned two years later, this was the moment he had been waiting for.

It was South Africa's le Clos who pipped him to gold in London, inflicting a shock defeat on the American who had won the event in 2004 and 2008.

Much of the talk ahead of the rematch in Rio had centered on Phelps' revenge mission -- and he didn't disappoint -- he smashed it.

Phelps, racing away on the final length, finished in a time of 1 minute 53.73 seconds with Japan's Masato Sakai taking silver and Hungary's Tamas Kenderesi claiming bronze.Le Clos, whose preparation for the Games has largely been overshadowed by the news that both of his parents were diagnosed with cancer, just missed out in fourth.

As the noise grew, Phelps stood tall and asked the crowd for more.

He returned to the pool for the men's 4x200 meter freestyle relay to ensure another gold medal ahead of Great Britain and Japan in a thrilling finale.

Phelps, along with Ryan Lochte, Conor Dwyer and Townley Haas, celebrated after claiming his 25th Olympic medal before taking time to rest.

Few could blame him after a hard night's work -- but while Phelps may be cooling down, Ledecky is only just getting started.Ledecky, chasing her second gold of the Games after winning the 400-meter freestyle, edged out Sweden's Sarah Sjostrom and Australia's Emma McKeon in a thrilling race.

The 19-year-old, who finished behind Sjostrom in her semifinal heat, took the race to her opponents to finish in 1 minute 53.73 seconds.

Ledecky, who is also hoping to successfully defend the 800-meter title that she won in London at age 15, has also already helped the United States claim silver in the 4x100 meter relay.

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Few would bet against her making it three golds, with the American holding the world record in the event."That hurt pretty badly," she told reporters after the race.

"It's the closest I've come to throwing up at the end of a race. I was just glad to get my hand on the wall first.

"It was a stressful race and I feel good now it's over. I took it pretty fast and forced everyone and once I was ahead I was not going to let it out of my hands."Katinka Hosszu claimed her third gold medal of the Games by winning the individual 200-meter medley after setting a new Olympic record.

The Hungarian, who had already won the 100-meter backstroke and 400-meter individual medley, finished just ahead of Great Britain's Siobhan-Marie O'Connor and American Maya Dirado.

Hosszu, nicknamed the "Iron Lady" could add another gold to her tally when she competes in the 200-meter backstroke.