World number one Iga Swiatek had to work hard to defeat lucky loser Kamilla Rakhimova in the first round of the US Open.

Swiatek from Poland was not at her best in her 6:4, 7:6 (8:6) victory in Arthur Ashe Stadium, which lasted just under two hours.

Swiatek, champion in New York in 2022, made her typical fast start and quickly took a 4-0 lead in the first set, but Rakhimova saved a break before Swiatek served out the set.

The number one seed broke early in the second set, but her frustration was clear as she angrily slapped at a ball after a long forehand gave her the break back.

Rahkimova, who lost in the last qualifying round, stayed in touch with Swiatek and had three set points in the tiebreak to force a deciding set.

But when it mattered, Swiatek increased her aggressiveness, secured the victory and agreed to a duel in the second round with the Japanese Ena Shibahara.

Five-time Grand Slam champion Swiatek won her third consecutive French Open title in June and secured an emotional Olympic bronze medal last month.

However, in her six appearances in New York, she only made it past the fourth round once – when she won the title two years ago.

“It was good at the beginning, but then I got a bit tense and my opponent took advantage of that, so I tried to get back to my game,” Swiatek said.

“I’m pretty sure I’m getting more rhythm every day.”