A first-time encounter between this summer's two Grand Slam breakout stars, Wimbledon champion Elena Rybakina and Roland Garros runner-up Coco Gauff, promised much in the second round of the National Bank Open.

It delivered twists, turns and an edge-of-seat climax before No.10 seed Gauff won through 6-4, 6-7(8), 7-6(3), sealing her fifth match point after missing four in the second-set tiebreak.

Here, we unpack what exactly went down over a wild 2 hours and 49 minutes with three key takeaways.

Gauff's resilience remains her forte: Gauff, 18, has never lost from match point up in her pro career. (The last time she did so at any level was in the 2018 Wimbledon junior semifinals to Wang Xiyu.) This remarkable record remains intact, though only just.

Gauff had been the better player off the ground during the first two sets, with Rybakina largely keeping in touch thanks to her serve. But big hitting from the Kazakh saved two of the first four match points, and Gauff was unable to control her groundstrokes on the other two. As Rybakina stole the second set and broke for 2-1 in the third, all the momentum was hers.

Even when Gauff emerged from a series of service breaks with a 5-3 third-set lead, she seemed fragile. Thirteen double faults mounted up, and Rybakina forced a tiebreak. But despite everything, Gauff was able to hold her nerve and hit her spots in the home stretch.

Contrasting strengths ... and weaknesses: If this was the first instalment of a frequent rivalry between two top players, the stylistic contrast on show bodes well. Rybakina's clean hitting was breathtaking at times, particularly in sealing set point to level the match, and garnered her 30 clean winners to Gauff's 23.

But it was ultimately undone by Gauff's remarkable, elastic defence. Time and again, the teenager tracked down Rybakina's hardest strikes and got them back into awkward positions; the longer a rally went on, the fewer options Rybakina seemed to have. Two consecutive points that saw Gauff move to 5-3 in the deciding tiebreak were emblematic of this.

One option Rybakina could have used in her arsenal was to finish points at net. The 23-year-old made her way there often enough, but too often was undone by poor volleying -- including a particularly unfortunate error to drop serve and trail 4-2 in the third set.

For Gauff's part, the double faults will be something to work on. Her tally of 13 was the most she has hit in a single match since losing to Ons Jabeur at Charleston 2021, and was a reminder of an old weakness that seemed to have been ironed out of her game. The most alarming aspect here was that they tended to come in batches on big points: three times down break point in the third set, three times serving at 4-2 and twice serving at 5-3.

All these takeaways could have been reversed: A tennis result is binary by nature: Gauff won and Rybakina lost, and thus we see it through the lens of Gauff winning because of her strengths and despite her weaknesses. But a tennis match is not at all black-and-white. Gauff won 116 points to Rybakina's 115, and this could just have easily swung the latter's way -- or, indeed, been wrapped up in straight sets by the former.

This time, Gauff's defence blunted Rybakina's power; Gauff was able to shake off her biggest weakness, while Rybakina couldn't overcome hers. Next time, the reverse could be true. And given what they brought in Toronto, we hope there will be many more times to come.