Naomi Osaka is the reigning US Open champion, the first Japanese to win a Grand Slam singles title and a fast-rising star of tennis — but do not call her cool.

Osaka bolstered her growing fame as she thrashed unseeded American Danielle Collins 6-1, 6-0 in 53 minutes to saunter into round three of the China Open on Tuesday.

Told afterwards that she had been branded “Queen of Cool” by an Australian tennis magazine, the 20-year-old looked startled.

“I don’t like the word ‘cool’ because then I feel like when someone meets me, they’ll be disappointed or something,” Osaka told reporters in Beijing.

“So they can use ‘expressionless’ or something,” she added with a smile, playing with the impression formed by some observers.

“I think actually I’m very emotional.”

Osaka, whose maiden Grand Slam was overshadowed by Serena Williams’s row with the chair umpire in their New York final, faces 10th seed Julia Goerges next at the China Open.

Osaka has booked her spot in the season-ending WTA Finals Singapore for the first time, underlining her blossoming potential.

But the world number six has appeared to struggle mentally with the fallout from the tempestuous final at the US Open, where Williams branded Carlos Ramos “a thief” and later accused him of sexism.

Osaka says her breakthrough victory last month was “bittersweet”, but has refused to point the finger at the American great.

Osaka was not the only handsome winner on Tuesday on Beijing’s outside hard courts.

China’s wildcard entry Wang Qiang continued her hot streak with a 6-0, 6-0 thrashing of Latvia’s 2017 French Open champion Jelena Ostapenko.

Ostapenko, the 12th seed, required treatment on her left wrist during the match and said afterwards that she had been playing at barely 50 percent because of the injury.

“I was trying to play until the last point because I really don’t like those retirements during the match,” said the 21-year-old.

Three-time Grand Slam winner Angelique Kerber is also into round three, along with reigning China Open champion Caroline Garcia of France.

Garcia will play Aryna Sabalenka after the Belarusian defeated former number one Garbine Muguruza in two high-quality sets, 7-5, 6-4.

In the men’s draw, top seed Juan Martin del Potro called for on-court treatment but was mostly comfortable in beating Spain’s Albert Ramos-Vinolas 7-5, 6-2 in his opener.

“It was a difficult start to the tournament for me,” said the giant Argentine, the losing US Open finalist, adding that he twisted his knee in the second half of the match.

“It was nothing dangerous,” he added.

“I served well, which is important for my whole game, but I didn’t feel with that strength during the game.”

Del Potro, enjoying the best season of his injury-disrupted career, faces Russia’s Karen Khachanov next.

Also safely into round two is second seed Alexander Zverev, who defeated Roberto Bautista Agut 6-4, 6-4, and third seed Grigor Dimitrov.

None of the “Big Four” of Roger Federer, Rafael Nadal, Novak Djokovic or Andy Murray are in action in Beijing.