Legendary swimming coach Bob Bowman said Sunday that he believes Leon Marchand can handle the pressure at next year's Paris Olympics after "a very good rehearsal" at the world championships.

French sensation Marchand has been one of the stars of the competition this week in Fukuoka, claiming three gold medals and breaking Michael Phelps's long-standing 400m individual medley world record.

Bowman mentored Phelps to unprecedented Olympic success and he now coaches Marchand at Arizona State in the US.

Marchand will face huge expectations at the Paris Games but Bowman said the 21-year-old "got better when the pressure was highest" this week in Japan.

"That's something Michael always did -- that's what the great ones do," said Bowman, who is serving as head coach of the US team in Fukuoka.

"When the pressure is on, they rise to meet it."

Bowman said Marchand shares the same "mindset" as Phelps, the most decorated Olympian of all time with a staggering 28 medals.

"That's something that Leon had to improve on to get to this level, so it's very good to see him develop into that kind of character," said Bowman.

Marchand broke Phelps's 400m IM record by more than a second on the competition's opening night, coming home in a time of 4min, 02.50sec.

Phelps's benchmark of 4:03.84 had stood since the 2008 Beijing Olympics and was swimming's oldest world record.

Marchand followed that up by winning the 200m butterfly and 200m IM titles.

Bowman said it "remains to be seen" what the Frenchman can achieve at the Paris Olympics.

"There is going to be a lot of expectations, but I feel like he's done a very good rehearsal this year and last year," he said.

"It's been good preparation for what will happen next year, and we'll try to carry that over into Paris."

The US have endured a disappointing world championships in Fukuoka under Bowman, and went into the final day with no hope of catching Australia in the medals table.

The Americans have won only four gold medals, compared to 13 for Australia and five for China.

Bowman said his team had made "a great effort".

"Obviously we like to win more gold medals and I think we will," he said.

"There are a number of reasons for that, both bigger-picture ones and smaller ones, but overall I'm pleased with how we raced."

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