The 2021 US Open has been full of nail-biting contests, and the latest was won by No.11 seed Belinda Bencic, who saved four set points in the first set before defeating No.7 seed Iga Swiatek 7-6(12), 6-3 in 2 hours and 7 minutes.

The thrilling 84-minute opening set culminated in the longest tiebreak (by points played) of the US Open so far, outdoing Simona Halep's 7-6(11), 4-6, 6-3 third-round scoreline against Elena Rybakina. The result puts Bencic into the last eight in Flushing Meadows for the third time in her career, having reached the quarterfinals as a 17-year-old on her 2014 debut and the semifinals in her most recent appearance in 2019.

Bencic has enjoyed a career surge this summer. Capturing the gold medal at the Tokyo Olympic Games has rejuvenated the former World No.4's game, and her wave of confidence was apparent in the contrast between this match and her last encounter with Swiatek.

Turning the tables: In the Adelaide final in February, Bencic lasted only 67 minutes in a one-sided 6-2, 6-2 rout by Swiatek. She could only muster six points on return. Seven months later, she had outdone that total before Swiatek had finished her second service game, and for most of the first set was in irresistible form as she turned the tables on her opponent.

It nearly wasn't enough. Swiatek was broken in the first game and spent the rest of the set barely clinging on to avoid the double break. The 20-year-old had to survive at least one deuce to hold her next three service games in the face of some breathtaking Bencic returns.

This tenacity seemed to have paid off as Bencic blinked serving for the set. A double fault from the Swiss invited Swiatek back into the contest, and she seized the momentum with stellar down-the-line winners of her own. Swiatek held her first set point at 6-5, and even after Bencic saved that, she retained control to take a 5-2 lead in the tiebreak.

How the epic tiebreak unfolded: From 2-5 down, Bencic rattled off four straight points to move to 6-5, and she would also lead 7-6 and 8-7. But after Swiatek saved that trio of set points, it was her turn to inch in front at 9-8 and 10-9 - the latter set up by a breathtaking 85mph forehand winner down the line.

Swiatek missed that chance by sending a putative volley winner wide, and even at that tense point could see the funny side, giving a sarcastic thumbs-up to her team. But after a fourth set point for each player came and went - Bencic at 11-10, Swiatek at 12-11 - it was Swiatek who finally buckled. Consecutive forehand errors from the former Roland Garros champion saw Bencic over the line on her fifth set point.

Stat corner: Both players had combined for 47 winners to 28 unforced errors in the spectacular first set - Bencic posting a 23-15 ratio, and Swiatek 24-13. Somewhat unsurprisingly, the air went out of the match in the second. Swiatek actually held the first break opportunity at 1-1, but squandered it with another forehand error. Bencic would break in the next game and then maintain that lead to the finish line, largely thanks to winning 74% of her first serve points.

Bencic on what she learned from Adelaide: "I definitely had an idea what she was going to do, what her plan would be. And also I was telling myself I improved a lot in certain areas of my game, which then makes the tactic for her a little bit different again. And then she kind of had to adjust that mid-match. I was kind of prepared for this, so I'm happy that worked well.

"You can never really rely on the past result for the next match."

- Belinda Bencic on avenging a prior loss.

"For sure, you want to take the experience from the last match, you know how it feels to play her. But then you don't really want to take the result as how it's going to be, because you can never really rely on the past result for the next match. It's always up and down, the conditions is different. Every match is just different, and it can be one week and then the next week and it's a complete different match."

Swiatek on what was different: "In Adelaide she just made mistakes. I was really solid. I just gave back some balls so she can make a mistake. Also, I had more winners. I mean, it felt like I had more winners there because I was in control.

"But here in really important moments, she backed out and she also was pretty solid. Like, last two balls of the match, I was the one who missed the last ball. So that was pretty frustrating, because I know that I can play really long rallies with a lot of topspin. She puts all the pressure on the opponents."

What's next for Bencic: The opportunity to reach her second straight US Open semifinal against teenage qualifier Emma Raducanu. Bencic has yet to play Raducanu.