Rybakina makes winning start in race to number one

Rybakina, a two-time Grand Slam winner, arrived at Flushing Meadows with question marks around her fitness after retiring injured against Iga Swiatek in Cincinnati.

Though she looked comfortable on court, her movement went largely untested by Frodin - who acted as Serena Williams' body double in the Oscar-nominated film 'King Richard' - as she blew the world number 585 away on serve and dictated points from the baseline.

"We will see day by day," Rybakina said about her injury. "I wasn't playing or doing much physically [in the build-up to the tournament].

"It's just one step at a time. The most important thing is to recover and listen to the body. For now, I'm ok."

After opening the rain-delayed match with a double fault, Rybakina proved relentless on serve, dropping just three points and reeling off three consecutive love holds in the first set.

She didn't face a break point until the sixth game of the second set, saving both.

Equally clinical in Frodin's service games, she converted her first three break points to race into a set and 5-1 lead.

However, the young wildcard, making her WTA Tour main-draw debut after winning the United States Tennis Association (USTA) Girls' 18s National Championship, made Rybakina work to get over the line, saving three match points with aces in her final service game among 11 across the match.

Rybakina served out the win with an ace of her own – her sixth of the match and tour-leading 363rd of the season.

"She played really well today. She has great shots, great serve, it was no easy," Rybakina said of the largely unknown Frodin.

"I'm just happy to be here. I really enjoyed it."