Ostapenko schools Gauff to return to the Grand Slam limelight

MELBOURNE, Jan 22 (Reuters) - Jelena Ostapenko emerged from four years in the Grand Slam wilderness to upset American seventh seed Coco Gauff 7-5 6-3 and reach her first Australian Open quarter-final on Sunday.

The 25-year-old Latvian had stunned the world in 2017 when she beat Simona Halep in the French Open final before being written off as a "one-Slam wonder" for failing to make much of an impression at the majors in recent years.

But on Sunday, on a Margaret Court Arena bathed in sunshine, Ostapenko announced her return to the big time with a power-hitting clinic against Gauff, the 18-year-old hyped as a title threat and potential long-term successor to Serena Williams.

"I always knew and believed in my game," Ostapenko told reporters.

"If I play well, I can beat almost anyone. I was trying to work more on my consistency, especially in the pre-season. Yeah, just to step on the court and play my game.

"I think I'm doing it quite well this week."

The win was Ostapenko's first over a top 10 player at a Grand Slam in three years and secured her first ticket to a major quarter-final since her run to the Wimbledon semi-finals in 2018.

Ostapenko was ruthless in the finish, unleashing a thumping forehand down the line to bring up match point, then clipping the line with a crosscourt forehand, her last of 30 winners, to give Gauff no chance.

The 17th seed will meet Elena Rybakina, who shocked top seed Iga Swiatek, for a place in the semi-final.

Ostapenko often seemed bewildered when the electronic system gave line calls against her, looking quizzically at her players' box on occasion.

Asked in her on-court interview whether she had faith in the system, Ostapenko replied: "To be honest, no. Honestly, this live electronic system ... I don't know, sometimes it feels like it makes some mistakes.

"Sometimes I know I'm wrong but I feel like some balls are pretty close when I look at my team. So I want to ask them what they think about the call."

A downcast Gauff converted only one of eight break points and was reduced to tears in the post-match media conference.

It was a big setback for the highly fancied American after reaching the final at Roland Garros and the U.S. Open quarter-finals.

"When you play a player like her and she plays really well, it's like, you know, there's nothing you can do," said Gauff.

"I feel like it was rough ... So it's a little bit frustrating on that part."

Reporting by Ian Ransom in Melbourne; Editing by Peter Rutherford

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