Sydney International

Ashleigh Barty broke Simona Halep's serve in the final game to beat the No. 1-ranked Halep 6-4, 6-4 in a second-round match Wednesday at the Sydney International.

It was Halep's first match since October after a lengthy layoff due to a herniated disc in her back. Halep won last year's French Open and lost to Caroline Wozniacki in the Australian Open final.

"I think it was a great match after almost four months since I played one full match, the U.S. Open," Halep said. "I think I played a good level of tennis. She played really well. Her slice was great today, so she deserved to win this match.

"But also I was very close to win. I had so many chances to break her and to take advantage, but I couldn't."

Halep said she was pain-free but would wait to see how she pulls up on Thursday before declaring that she is over the back injury.

"No pain at all. I'm happy about that. It's a great sign," she said. "I will recover now, and I will see how I wake up tomorrow morning."

Barty served five aces, no double-faults and broke Halep three times to reverse two previous losses to Halep last August.

"I finally learned my lesson," Barty said. "She gave me a belting in Montreal. I learned a little bit more in Cincinnati, but today I knuckled down and really thought about it and really gave myself a chance.

"The biggest thing, I believed that I could I win. We're both out here on the same court. Just very happy I was able to come out and execute."

The 27-year-old Halep will be at the Australian Open next week in Melbourne without a coach after parting ways with Australian mentor Darren Cahill, who can longer commit to Halep due to family reasons. Cahill had coached Halep for four years.

In first-round matches, 10th-seeded Elise Mertens beat qualifier Katerina Siniakova 7-6 (4), 2-6, 6-2 and Anett Kontaveit defeated Monica Puig 2-6, 7-5, 6-1.

In the second round, Timea Bacsinszky defeated Samantha Stosur 5-7, 6-4, 6-3 and Yulia Putintseva beat fourth-seeded Sloane Stephens 3-6, 7-6 (4), 6-0.

In men's play, Alex de Minaur beat American qualifier Reilly Opelka 6-4 7-6 (4) in a match suspended by rain after just one game on Tuesday night to advance to the quarterfinals against fellow Australian Jordan Thompson.

"I think I got lucky today. Reilly's an incredibly tough opponent," de Minaur said. "I took care of my chances. I would have loved to get the break in the second. I had a couple of chances, but I did well to focus on my serve and I'm glad things went my way today."

In other second-round matches, top-seeded Stefanos Tsitsipas defeated Guido Andreozzi 6-3, 6-4, third-seeded Diego Schwartzman beat qualifier Guillermo Garcia-Lopez 6-2, 6-3, and fourth-seeded Gilles Simon defeated Sam Querrey 7-6 (5), 6-7 (6), 6-4.

ASB Classic

Top-seeded John Isner was eliminated in the second round of the ATP Tour's ASB Classic, losing 7-6 (3), 7-6 (5) to fellow American Taylor Fritz.

On a good day for young Americans, Tennys Sandgren of the United States beat third-seeded Marco Checchinato of Italy 6-3, 6-3.

Isner's defeat was another blow to a tournament already deprived of star power by the withdrawals of Gael Monfils, Roberto Bautista Agut and Tomas Berdych and the first-round losses of Hyeon Chung and Denis Shapovalov.

Fritz had lost to Isner in their two previous meetings but prevailed Wednesday in the face of Isner's barrage of 26 aces. The 21-year-old Fritz, ranked 50th, managed to beat his 10th-ranked compatriot for the first time by winning a handful of key points in both tiebreaks.

"It feels great," Fritz said. "John's beaten me twice before and it was close.

"I really wanted to get the win on him and I knew I could. We had a lot of close points and it just feels really good to get through that."

Fritz achieved the rare feat of breaking Isner's serve in the fifth game of the first set. He earned three break points and Isner saved the first two with aces but Fritz converted the third for a 3-2 lead. Isner broke back immediately and held for the rest of the set to set up the tiebreak.

Fritz immediately grabbed a mini break and took a 3-0 lead. Isner battled back with two aces but couldn't disrupt Fritz's serve — he served 12 aces of his own — and the younger American took the set in 53 minutes.

The second set went to a tiebreaker without a service break, Fritz saving the only break point of the set in the third game. Fritz again took the early advantage, gaining a mini break on the third point and serving for a 4-1 lead.

This time Isner broke back for 4-4 but Fritz took a point against serve again at 6-4, sweeping a backhand winner across court as Isner advanced on the net.

Fritz won more tiebreaks in 2018 than any other player and he put that ability to good use Wednesday to claim his fourth win over a top-20 player.

"I like to think that one of the strengths of my game is playing under pressure and playing the big moments well," Fritz said. "More often than not in the matches I lose that's where I get let down.

"So I'm happy to start every year and today as well playing well under pressure and handling those big moments well."

Meanwhile, five-time champion David Ferrer's final appearance at the ASB Classic ended in unfortunate circumstances when he was forced to quit his second-round clash against Pablo Carreno-Busta with a calf injury.

The score was tied 1-1 in the opening set when Spain's Ferrer was forced to withdraw. He was leading 15-0 in the third game when he swiveled awkwardly while playing a forehand near the net.

After receiving medical attention, he returned to the court to play one more point before withdrawing.

Ferrer is playing his last season on the ATP Tour and chose Auckland, which he has played for the last 14 years, as one of six tournaments on his 2019 farewell tour.

Hobart International

Belinda Bencic eased into the quarterfinals at the WTA Tour's Hobart International, beating Australian wild card Zoe Hives 6-2, 6-4.

Hives pulled off an upset when she beat Johanna Larsson to reach the second round but couldn't repeat that form against a polished Bencic, who set up a quarterfinal against 18-year-old Ukrainian Dayana Yastremska.

Seventh-seeded Kirsten Flipkens moved into the final eight with a 6-7 (3), 6-4, 6-1 win over Slovakia's Viktoria Kuzmova 6-7 (3) 6-4, 6-1.

Earlier, Anna Karolina Schmiedlova of Slovakia continued her strong start to the new year, beating eighth-seeded Alison Van Uytvanck.

A winner of three singles titles on the WTA Tour and 12 more on the ITF circuit, the 24-year-old Schmiedlova is on the rise again after reaching a ranking peak in 2015 only to drop out of the top 100 the following year.

She began 2018 ranked 132 but broke back into the top 100 and finished the year ranked 74.