How Coco Gauff Escaped a Trap of Her Own Making

Also today: Jannik Sinner’s near-unbreakability

Coco Gauff is not a pusher, but she can do an awfully good impression of one. In yesterday’s Australian Open quarter-final against Marta Kostyuk, the American coughed up 50 unforced errors against just 17 winners. The average rally lasted 4.6 strokes, a modest number that was rescued from marathon territory only by Gauff’s many unreturned serves.

Coco’s forehand, the usual culprit when things get messy, was on full display yesterday. While the stroke has shown signs of improvement–only 9% of them contributed to the unforced error tally, below both tour average and Gauff’s own standard–it remains loopy, and it gets ever-more cautious under pressure. Kostyuk was willing to go after the high-bouncing mid-court groundstrokes, often putting Gauff on the run. Fortunately for the American, her defense rarely deserts her. She eked out a three-hour, 7-6, 6-7, 6-2 victory for a place in the Melbourne semi-finals.

My impression watching the match was that Gauff put an unreasonable number of returns–especially forehand returns–in the middle of the court, not too deep, and that Kostyuk was punishing them. I was partly right: The Ukrainian forced Coco to hit forehand after forehand against the serve, more than two-thirds of her service returns all told. Gauff did indeed send more of those balls down the middle, closer to the service line than the baseline. And Kostyuk attacked… but to little avail.

Let’s get into the numbers. The Match Charting Project divides the court into thirds, both in terms of direction (forehand side, backhand side, and middle) and depth (shallow [in the service boxes], deep [closer to the service line than the baseline], and very deep). All else equal, shots deep and/or to the sides of the court are better, though of course they are riskier. Some returns will inevitably end up down the middle and shallow; the goal is only to avoid it when possible.

Here is how Gauff’s performance yesterday compared to tour average and her own typical rate of service returns that went down the middle and didn’t land close to the baseline:

RETURNS          Middle/Not Very Deep  
Tour Average                    34.0%  
Coco Average                    40.5%  
Coco vs Kostyuk                 43.7%

Indifferent return placement is nothing new for the American, and she left even more hittable plus-ones for Kostyuk than usual. It wasn’t as bad as last year’s US Open final against Aryna Sabalenka, when Gauff put more than half of her returns in the less effective zones, but Kostyuk is no Sabalenka when it comes to imposing her will with the serve.

Return placement matters. On average, tour players win 46% of points when they land a down-the-middle, not very deep return. When they put the ball anywhere else–closer to the baseline or a sideline–they win 56%. Gauff is a little better behind the weak returns, but for her career, the gap is still present: 47% versus 55%.

Except… that isn’t what happened yesterday!

RETURN OUTCOMES  Mid/NVP W%  Better W%  
Tour Average          46.2%      56.3%  
Coco Average          46.9%      54.8%  
Coco vs Kostyuk       60.0%      55.2%

When Gauff placed a return near a line, her results yesterday were typical. But Kostyuk was unable to capitalize on the rest. Among 88 matches logged by the Match Charting Project, Gauff has won 60% of those middle/not-very-deep returns only a dozen times, usually in blowouts.

Judging from the American’s performance on return, she could have made quick work of yesterday’s contest, too. The sticking point came on her own side of the ball, where her non-committal forehands didn’t work out as well.

Minus-ones

On the WTA tour, when the return lands in play, the server has nearly lost her advantage. A good first serve can give her a lingering edge, or a well-placed return can tilt the balance in the other direction, but overall, the point begins again as a neutral proposition. Servers win 52% of those points.

Gauff, on average, does a little better, converting her serve 53% of the time. There are signs she’s improving, as well. In the US Open final against Sabalenka, she won 55%, and in the Auckland final this month versus Elina Svitolina, she picked up 59%. Apart from lopsided matches, the high-50s are the best anyone can do on an ongoing basis: Iga Swiatek’s average is 57%, and Sabalenka’s is 55%.

Coco won 39% against Kostyuk.

Gauff’s lack of confidence in her forehand showed up in multiple ways. First, she didn’t use it as much as a plus-one weapon. She usually hits 57% of her plus-one shots from the forehand side, in line with tour average. Yesterday, that rate was just 51%, something that had more to do with her own choices than any return magic that Kostyuk conjured up.

Then, she didn’t do much with those forehands. The following table shows plus-one forehand rates (3F%), the percentage of plus-one forehands hit down the middle (FH Mid%), and the server’s winning percentage (FH Mid W%) behind those down-the-middle forehands:

PLUS-ONES          3F%  FH Mid%  FH Mid W%  
Tour Average     56.6%    29.9%      45.9%  
Coco Average     57.2%    35.0%      47.0%  
Coco vs Kostyuk  50.7%    39.5%      40.0% 

Gauff magnified her own tendency to go back down the middle with her second-shot forehand. It didn’t work, as she won just 40% of those points, compared to her typical rate of 47%.

Even beyond the plus-one, Coco just kept pushing the forehand. She went down the middle with 46% of her forehands, compared with her usual 37% and the tour average of 28%. She won barely one-third of the points when she did so, partly because of the nine unforced errors she racked up playing an already conservative shot. Two of those missed down-the-middle forehands came on back-to-back points when she could hardly afford them, taking her from 15-all to 15-40 when trying to close out the match at 5-3 in the second set.

In the end, as we’ve seen, Gauff’s defense saved her. She won more than half of Kostyuk’s serve points despite lackluster returning. Had she served just a little better–she missed six straight first serves in that 5-3 game–she would have finished the job an hour sooner. Had she attacked a bit more effectively with her second shots, even the off-day from the line wouldn’t have amounted to much.

To state the obvious: She’ll have to play better to beat Sabalenka in tomorrow’s semi-finals. One thing, at least, will work in Coco’s favor: She’ll have many fewer choices to make. The defending champion will dictate play and give her less time to think than Kostyuk did. Gauff withstood the Belarusian barrage in New York, winning the US Open title despite a couple of detours against less aggressive players in the early rounds. The American can’t play tomorrow like she did yesterday, but thankfully, Sabalenka won’t let her.

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Jannik Sinner’s near-unbreakability

Jannik Sinner has lost his serve just twice en route to the Australian Open semi-finals. He has faced 28 break points and saved 26 of them.

Since 1991, when the ATP started keeping the relevant stats, he is the 26th player to reach the final four at a major with so few breaks of his own serve:

Tournament  Semi-finalist       BP Faced  Broken  
2013 USO    Rafael Nadal               6       0  
2018 Wimb   John Isner                 7       0  
2015 Wimb   Roger Federer              3       1  
1994 Wimb   Pete Sampras               9       1  
2015 AO     Novak Djokovic            11       1  
2014 Wimb   Roger Federer             12       1  
1997 Wimb   Pete Sampras              12       1  
2010 USO    Rafael Nadal              14       1  
2012 RG     Rafael Nadal              17       1  
2004 Wimb   Roger Federer             17       1  

Tournament  Semi-finalist       BP Faced  Broken  
2014 Wimb   Milos Raonic               9       2  
2011 RG     Novak Djokovic*            9       2  
2007 USO    Roger Federer              9       2  
2006 Wimb   Roger Federer              9       2  
2006 Wimb   Rafael Nadal               9       2  
2015 USO    Roger Federer             11       2  
2014 AO     Roger Federer             11       2  
1997 USO    Greg Rusedski             11       2  
1993 AO     Pete Sampras**            12       2  
2013 Wimb   JM del Potro              13       2  
2019 AO     Rafael Nadal              15       2  
2008 Wimb   Roger Federer             15       2  
2005 AO     Andy Roddick              15       2  
1998 Wimb   Pete Sampras              17       2  
2000 AO     Yevgeny Kafelnikov        22       2  
2024 AO     Jannik Sinner             28       2

* Djokovic won one round by W/O and another by retirement
** I don't have stats for Sampras's QF, but the final score suggests that he wasn't broken

Pretty good company! As the table makes clear, though, Sinner’s 28 break points faced is not so elite. In fact, the average major semi-finalist faces exactly 28 break points in his first five matches.

The Italian’s accomplishment, then, is saving so many. 26 of 28 is a 93% clip, and that is more rarefied air:

Tounament  Player      Faced  Saved   Save%  
2013 USO   Nadal           6      6  100.0%  
2018 Wimb  Isner           7      7  100.0%  
2012 RG    Nadal          17     16   94.1%  
2004 Wimb  Federer        17     16   94.1%  
2010 USO   Nadal          14     13   92.9%  
2024 AO    Sinner         28     26   92.9%  
2014 Wimb  Federer        12     11   91.7%  
1997 Wimb  Sampras        12     11   91.7%  
2015 AO    Djokovic       11     10   90.9%  
2000 AO    Kafelnikov     22     20   90.9%

Things will get tougher on Friday, when Sinner faces all-time-great returner Novak Djokovic for a place in the final. Then again, Djokovic failed to convert his first 15 break points against Taylor Fritz yesterday–maybe he was just preparing for the matchup with Sinner.

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