Australia's world number one Ashleigh Barty marked her return to the court with a gritty win against American teenager Coco Gauff in Adelaide.

Gauff, 17, led 6-4 4-3 and had a double break point, only for Barty to save it and then turn the match around.

Barty levelled before dominating the deciding set to seal a 4-6 7-5 6-1 win.

Two-time Grand Slam champion Barty is the favourite to win the Australian Open, which starts in Melbourne on 17 January, and will be looking to become the first home player to win the Grand Slam since 1978.

"I felt like I played a pretty good quality match considering it was my first match in a few months," said 25-year-old Barty, who faces American Sofia Kenin or fellow Australian Ajla Tomljanovic in the quarter-finals.

"Coco played great and forced me to hit a lot of balls. I felt I got better and better as the match went on. It was nice to get some court time."

Second seed Aryna Sabalenka suffered a shock exit in Adelaide, losing 7-6 (7-6) 6-1 to Slovenia's Kaja Juvan, who is ranked 100th in the world.

In Melbourne, British number three Harriet Dart lost to American Madison Keys in the first round of the Summer Set Two event.

Dart, 25, won two qualifying matches to reach the main draw of the tournament, which is one of a pair of WTA 250 events being held at Melbourne Park before the Australian Open starts.

The world number 123 was unable to earn another victory as Keys, the 2017 US Open finalist who is now ranked 56th, won 6-3 7-6 (7-2).