Elina Svitolina returns against Katerina Siniakova. Photo: Seth Wenig, AP

NEW YORK – Ukraine’s fourth-seeded Elina Svitolina, fighting to become world number one, and Austrian sixth seed Dominic Thiem captured rain-interrupted matches on Wednesday to reach the second round of the US Open.

Svitolina, seeking her sixth title of the year and first Grand Slam crown, held off 42nd-ranked Czech Katerina Siniakova 6-0 6-7(5) 6-3, while Thiem finished off Australian Alex de Minaur 6-4 6-1 6-1 under sunny skies.

There were 87 matches scheduled Wednesday in the year’s final Grand Slam event after rain washed out most of Tuesday’s agenda, 11 of them halted first-round affairs.

Former world number one Maria Sharapova, who in her Grand Slam return from a 15-month doping ban upset second-ranked Simona Halep, was set to face Hungary’s 59th-ranked Timea Babos in a later second-round match at Arthur Ashe Stadium.

Sharapova played only one hardcourt tune-up match due to a forearm injury, but powered past one of seven contenders for the world number one ranking still in the field.

Another of those is Svitolina, who dropped six of nine tie-breaker points when her match resumed, but survived a third set, breaking for a 4-2 edge and serving out for the victory.

“It was a little bit unlucky to stop because I was playing good,” Svitolina said. “Today was a little bit of a mess in my head. It was tough to keep my focus. I’m happy I could win the third set and play really good tennis.

“I was just trying to fight for every ball. You can’t win if you’re not mentally strong.”

Thiem, a semi-finalist at the past two French Opens, was working to adapt his skill on the Paris red clay to maximum impact on the New York hardcourts.

“I’m pretty pleased with the performance,” Thiem said. 

“I’m trying to improve my hardcourt game. I cannot play my clay game here. I can’t stay close to the baseline.”