INDIAN WELLS, CA, USA -- In the longest match of the 2019 season to date, No.6 seed Elina Svitolina of Ukraine survived an incredible barnburner against No.12 seed Ashleigh Barty of Australia, 7-6(8), 5-7, 6-4, to reach the quarterfinals of the BNP Paribas Open for the first time in her career.

"It felt pretty long, because we had long rallies and long games," Svitolina told the press, after she was told it was the longest match of the year. "It actually felt longer than three hours, 12 minutes," she added with a smile.

Svitolina came into the encounter with a 4-0 head-to-head record against Barty, but the Australian pushed her to the very limit this time before Svitolina emerged victorious after a grueling three hours and 12 minutes of play. Svitolina held two match points in the second set before Barty fought back to force a decider, in which Svitolina had to come back from a break down.

"I always trust my fitness," said Svitolina. "I know that I can play good matches, and I'm physically strong. It's one of my strengths, I would say, so I have just to trust it. You know, I was working before coming here on my fitness. So I just had to go out there and to stay tough and fight until the very last point, and it really helped me today."

Svitolina moves into the quarterfinals, where she will face 19-year-old Czech Marketa Vondrousova. The teenager picked up the first Top 10 win of her career when she shocked No.2 seed Simona Halep in three sets earlier on Tuesday. Svitolina leads their head-to-head 2-0, with both wins coming last year.

"[Vondrousova's] spin is a little bit different because she's left-handed," said Svitolina. "I have to adjust to this. For me, it's just important to bring my game."

The players both held onto their service games with ease up to 4-4, but things changed from there. Barty had only dropped four points on serve up to that point, but the Australian got into trouble in that game. Barty fended off three break points with good aggressive play, but an unforced error gave Svitolina a fourth chance to break, which Barty ceded with a double fault.

However, Svitolina was unable to take advantage when serving for the set at 5-4, dropping serve at love in a slew of unforced errors. The Ukrainian then needed to survive a set point in her next service game, eventually drawing an error from Barty, then pulling out the game to set up a tiebreak.

At 3-3 in the breaker, Barty crushed a forehand winner crosscourt to gain a mini-break, then held her two service points handily to gain three more set points. But miscues by the Australian on all three leveled the tiebreak once more at 6-6. A forehand winner gave Barty a fifth set point at 7-6, but she squandered that one as well with a backhand error.

It was then Barty’s turn to face set points. The Australian saved one at 8-7 with a strong serve, but Svitolina claimed another after a rally ended with a Barty forehand error. The set finally came to a conclusion after just over an hour when Svitolina converted her second set point due to a Barty backhand into the net, giving the Ukrainian the tiebreak by 10 points to eight.

Svitolina kept the momentum going, taking a 3-1 lead by breaking Barty on her fourth break point of the game. But Barty refused to give in so easily, breaking right back with a backhand winner after an all-court rally. But Svitolina claimed the the lead again, taking advantage of Barty’s forehand errors to break for 5-3.

Serving for the match, Svitolina dropped serve after a barrage of big forehands by Barty. However, in the following game, Svitolina held two match points after forehand errors by the Australian. Barty fended those off with winners from her forehand side, then polished off the game from deuce with tremendous serves for 5-5.

The Australian was rewarded for that effort with an error-filled game from Svitolina, as the Ukrainian dropped serve at love. Barty served for the set at 6-5, and missed four set points, allowing Svitolina to claw back to break point. But Barty was able to use big hitting to get two more chances, and she converted her sixth set point to level the match.

The combatants moved into the deciding set having played two preceding sets which each took over an hour. Barty, using her verve from her second-set comeback, broke Svitolina in the opening game with a backhand passing winner that fell right in the corner of the court. But Svitolina pulled back level with a break for 3-3 after an error-forcing volley.

Svitolina claimed a second straight service break, this time at love, to reach 5-3 and serve for the match for the second time -- but the first time in the third set. Once again, Svitolina was unable to seal the deal, firing a backhand error long on Barty’s second break point of the game.

The Ukrainian, though, garnered three match points in the subsequent game. Though Barty erased two with strong serving to pull back to deuce, a deep return by Svitolina led to a netted forehand on the No.6 seed’s third match point of the game and fifth match point overall.