Flavia Pennetta won her 1st Grand Slam and then rode off into the sunset

Following our recent series on the best teams never to win a championship, we’re flipping the concept. This series will examine a selection of the most unlikely teams to reach the mountaintop. These teams can be ones that got hot at the right time, or those who belong to franchises that have not often tasted the Champagne of champions.

It’s impossible to talk about Flavia Pennetta’s 2015 US Open title without also talking about her Italian compatriot, Roberta Vinci. No retelling of that wildly improbable event would be complete without both of them. Or, for that matter, without Serena Williams.

The US Open that year was all about Serena’s pursuit of a calendar Grand Slam. She won the first three Slams of the year, and won the US Open the year prior, so as it was she held all four major titles at once. She’d done that before, 13 years earlier, but had never won all four in the same year.

Another Slam crown would give her 22 for her career, tying Steffi Graf for the most in the Open era. Williams arrived in Flushing Meadows with a 45-2 match record in 2015.

On the other side of the bracket, a 33-year-old Pennetta, ranked 26th in the world and in the midst of an up-and-down season, was playing in her final Grand Slam tournament. She knew it, but the rest of the world did not. What the rest of the world knew was that Pennetta had been struggling. She had a modest 16-15 record on the season and was bounced in the first round at seven of the 15 events she’d played, including two of the year’s first three majors. She’d won just two matches in the five events she played since the French Open.

Pennetta had, to that point, enjoyed a successful career that included 10 singles titles, six Slam quarterfinal appearances, and a US Open semifinal berth in 2013. She ranked as high as 10th in the world. She won the biggest title of her career at Indian Wells 18 months earlier. She had a steady, balanced, intermittently powerful game, with a particularly strong backhand.

But she never broke through to become a reliable contender at the biggest events. Her serve and forehand were solid but unspectacular, and she lacked a dominant weapon. She underwent major wrist surgery in 2012 that threatened to derail her career, and she later admitted that she pondered retirement every year thereafter. By the fall of 2015, she was seemingly past her peak.

She also struggled at times to manage her emotions. Perhaps her most memorable match that season was during her Indian Wells title defense, when she was suddenly and swiftly overwhelmed by a tidal wave of angst in the middle of a fourth-round faceoff against Maria Sharapova, crying openly on court before recovering her composure and coming from behind to win.

Gary Hershorn / Corbis Sport / Getty

Pennetta played well, if unevenly, through the first week of the US Open. In the third round, she dropped the opening set 6-1 to journeywoman Petra Cetkovska, before bouncing back to win the second in equally lopsided fashion and holding on to win a tense third.

After cruising past 2011 champ Sam Stosur in the fourth round, she met world No. 4 Petra Kvitova in the quarterfinals, and gutted out a seesawing three-setter in which she was able to redirect Kvitova’s immense power and use sly angles to move the big Czech around the court. Calmly, quietly, Pennetta was playing some of the best tennis of her career.

But, like everything else that happened during that fortnight in New York, her exploits were obscured by the shadow of Serena’s historic chase, which consumed the tournament, the tennis world, and ultimately Serena herself.

On the day of the women’s semis, Serena and Simona Halep appeared to be on a collision course. They were ranked No. 1 and 2 in the world, and had been playing epic matches in the latter stages of big tournaments all year. Halep had come up on the losing end of those matches, but showed she was plenty capable of pushing Serena to her limits. If anyone was going to derail the calendar Slam, it seemed like it would be Halep.

But in the first semifinal of the day, Pennetta played the match of her life, upending the fleet-footed Romanian in two dominant sets with a master class in smart, attacking tennis. Pennetta’s best shot, her cross-court backhand, was never cleaner or more deadly than it was that day. Halep couldn’t get so much as a toehold in the match. Pennetta kept her on the back foot, pinned behind the baseline, the entire time.

The defining stretch of the match came in the second set, after Halep secured a second straight break of serve and appeared to be turning the tide. Pennetta responded by winning the next 15 points, cracking winners off both wings.