The 22-year-old French star left no doubt he'll be remembered as one of the biggest stars of the Summer Games in his home country. He touched in an Olympic record of 1 minute, 54.06 seconds, just missing Ryan Lochte's 13-year-old world mark.

That was about the only thing he didn't accomplish at La Defense Arena, where he had previously won the 400 IM, 200 butterly and 200 backstroke — the latter two about two hours apart in the same night.

Before Marchand's triumph, Cameron McEvoy and Kaylee McKeown won more gold for Australia.

McEvoy touched first in the 50 freestyle, denying Caeleb Dressel a repeat in swimming's most frantic event. McKeown followed with a victory in the 200 backstroke to become the first female swimmer to sweep the back at two straight Summer Games.

McEvoy became the first Australian man to win gold at these games, and McKeown quickly boosted her country's total to a leading seven golds overall.

McEvoy made it from one end of the pool to the other in 21.25, edging Benjamin Proud of Britain by five-hundredths of a second. Florent Manaudou of France thrilled the home crowd by taking the bronze in 21.56.

Dressel, who won five gold medals at the Tokyo Olympics, finished sixth in 21.61.

McKeown rallied again, just as he did in the 100 backstroke, to chase down perennial American runner-up Regan Smith. The winning time was an Olympic-record of 2:03.73, breaking the mark that Missy Franklin set at the 2012 London Games.

Smith touched in 2:04.26 for the fifth silver medal of her career, to go along with a single bronze. She had yet to win gold.

The bronze went to Canada's Kylie Masse in 2:05.57.