Daria Saville and Ajla Tomljanovic have made winning starts to their US Open campaigns, and have both set up second round clashes with two of the tournament favourites. 

Saville has a second-round showdown with world number one and defending champion Iga Świątek, while Tomljanovic will take on fourth seed Elena Rybakina.

Saville, a  former top-20 star, looked anything but a player on the comeback trail from a serious knee injury as she routed American teenager Clervie Ngounoue 6-0, 6-2 in little more than an hour.

Saville broke the 17-year-old seven times, never faced a single break point on her own serve and finished with 16 winners and just 13 unforced errors for the match.

"I was very composed," Saville said.

"When the day started I was pretty relaxed. I don't know why — it doesn't really happen on day one of a grand slam.

"Warming up before the match I was like 'Um, this feels like just a normal match' and that felt nice and I think that is why I played well."

Playing the Open on an injury-protected ranking after being sidelined for more than eight months, Saville knows she will need to find another level against Świątek on Thursday (AEST).

"Well, the biggest goal is not to get double bageled," she said.

"I am excited. Hopefully we'll get to play on the big court. When I was coming back from injuries that was like the goal — get to play on all the bigger courts at every slam and hopefully that will be ticked off.

"I think I can still make her life very uncomfortable. I will just play free and see what happens.

"Forehand is my weapon and, when it's working, this is when I am dangerous.

"Obviously I have to move well to get to use my forehand but today I also served pretty well, hit my spots well. It is part of my game hunting forehands."

The Polish world number one Świątek took just under an hour to take care of Sweden's Rebecca Peterson 6-0, 6-1.

Tomljanovic comes from set down to defeat Panna Udvardy

Ajla Tomljanovic has overcome a slow start to win her first round US Open match against Hungary's Panna Udvardy.

Australia's second highest ranked female player powered home in the second and third sets to win 3-6, 6-2, 6-4.

Her win sets up a second-round clash with fourth seed Elena Rybakina, who cruised past her Ukrainian opponent Marta Kostyuk 6-2, 6-1 on Tuesday.

Tomljanovic, who has been sidelined since November, started off well in the opening set, breaking Udvardy's serve in the opening game.

Her advantage did not last long, as the Australian was broken on her first four games on serve.

Tomljanovic was quickly able to dust off the first set, winning the opening three games, including a break of serve, to take command of the second set.

But Tomljanovic's future in this year's US Open looked uncertain when she was broken to love in the opening game of the deciding set.

She was able to square the set in the fourth game at 2-2, breaking Udvardy's serve in a tense battle. 

Heading into the 10th game leading 5-4, Tomljanovic broke serve for the seventh time in the match to claim victory. 

Meanwhile, wildcard Rinky Hijikata has progressed through to the second round of the men's singles, with a four-set win over Pavel Kotov.

The Australian needed just under four hours to take a 7-5, 5-7, 6-3, 7-5 victory and set up a second round clash with Hungary's Marton Fucsovics.

Alexei Popyrin falls in four sets to Stricker

Alexei Popyrin's recent run of form has not carried over into the final major of the season, with the Australian losing to Swiss qualifier Dominic Stricker in four sets.

Popyrin, who won the Croatia Open and was a quarterfinalist at the Cincinnati Masters in the past month, committed 46 unforced errors in his 3-6. 4-6, 6-3, 3-6 defeat.

Lone breaks for Stricker in each of the opening two sets gave the Swiss a massive advantage, leaving Popyrin with a mountain to climb to get into the second round.

The Australian was finally able to get a break of serve in the eighth game of the third set, clawing the match back to 2-1.

But Stricker was able to find another gear in the fourth, winning the opening five games.

Popyrin was able to get one break back, but it was too late for the Australian, who bowed out in the first rounds of the French Open and Wimbledon this year.

Hunter, Birrell and Gadecki bow out in first round

Storm Hunter's US Open singles run lasted just 65 minutes, with the West Australian going down to Czech 10th seed Karolina Muchova.

Hunter was in the contest in the opening set against the 2023 French Open finalist, breaking serve in the eighth game of the opening set to level it at 4-4.

Unfortunately for Hunter, that is as close as she got to the Czech, who went on to win the next two games, then beating her to love in the second set.

The 4-6 0-6 defeat lasted just over an hour, with Hunter now turning her attention to the women's doubles, where she is partnering Elise Mertens from Belgium.

Kim Birrell also fell in the opening round to American Jennifer Brady. 

The 3-6 6-7(4) defeat lasted one hour and 54 minutes.

Olivia Gadecki fell to teenager Mirra Andreeva despite an impressive start.

Gadecki, a qualifier, won the opening set 6-1, but her Russian opponent turned the tables in the second set. 

The Australian won the opening two games in the second, but then conceded the next five.

Gadecki was broken in her first two service games in the deciding set, the second ultimately being the crucial moment for her Russian opponent, who ran out the victor 1-6, 6-3, 6-4.

AAP/ABC