Hingis books Seles date

Hingis was vulnerable on her serve

Martina Hingis earned a fourth round meeting against Monica Seles after beating Amanda Coetzer in straight sets at the US Open.

The ninth seed won 6-3 6-4 in 74 minutes but was not entirely convincing against the experienced South African who is unseeded this year.

It will be an intriguing clash against Seles, another former world number one who is looking to recapture her Grand Slam-winning days.

Women's round-up

Both players struggled to finish off their third round matches, with Hingis still struggling for her best form after returning to the Tour following injury.

My brain went away from the court. Definitely checked out

Monica Seles

Her serve in particular looked vulnerable and it will need to improve if she is to challenge the dominance of the Williams sisters once again.

Hingis began brightly against Coetzer, breaking her in the fourth game.

Coetzer hit back with a break in the seventh game but Hingis immediately restored her advantage and then held to take the first set in 24 minutes.

Photo Gallery: women's day six action

The second set was a see-saw affair with the first five games going against serve.

Hingis finally managed to hold in the sixth game and then held out for her eighth consecutive win against the South African.

The match was the first of the night session, which also included Jennifer Capriati's victory over Meghann Shaughnessy.

Seles struggles

It was the first time in US Open history that the night session was dedicated exclusively to women's matches.

Earlier, sixth seed Seles made hard work of seeing off qualifier Yoon Jeong Cho.

Leading 6-1 5-1, the former two-time champion was seemingly cruising into the fourth round.

But then she lapsed into a series of unforced errors and allowed the determined Cho to claw her way back.

Game-by-game: Seles v Cho

Cho won seven games in a row to take the second set and force a decider.

Seles grew increasingly frustrated as she struggled with her serve and committed countless unforced errors.

"The only person to be mad at is myself," Seles said afterwards. "What can you do? My brain went away from the court.

"It just went away when it shouldn't. Lesson learned. Definitely checked out of the tennis court."

The 28-year-old American finally emerged a 6-1 5-7 6-4 winner after nearly two hours.

"I'll have to play a lot better if I am going to advance much further," Seles added.