It was the hand signal that was supposed to change the game. Patrick Mouratoglou, coach of Serena Williams, lifted his hands from his lap, palms parallel, and made a few poking motions. He was trying to convey that Williams, who had just lost the first set of the 2018 US Open women's final, needed to move forward and play from further inside the court.
We all know what happened next. Chair umpire Carlos Ramos happened to catch the subtle gesture. He issued Williams a code violation for coaching. Within moments, a sensational controversy that would rock the sporting world began to unfold.
In the wake of that incident -- and some heavy lobbying by, among others, Mouratoglou -- many believed that tennis officials would finally embrace some form of permissible coaching.
It hasn't happened.
For the third consecutive year, the US Open will allow on-court coaching in qualifying, junior and wheelchair events. But tournament officials have backed away from a plan to allow some form of coaching in the main men's and women's draws.
"Although we feel strongly regarding this issue, our goal is to work collaboratively with all tennis governing bodies to build a consensus before moving forward." Chris Widmaier, the USTA's director of communications, told ESPN.com.
"Consensus" on this issue might be a long time coming because on-court coaching at the Grand Slam and ATP Tour level (it's already established on the WTA Tour level) is the most divisive issue in tennis -- so much so that the game is in gridlock over it. The demonstrably wrong line calls that probably cost Williams her US Open quarterfinal match with Jennifer Capriati in 2004 impelled the USTA to introduce Hawk-Eye electronic line-calling the following year. This time, the rush to reform stalled in its tracks.
One large, powerful constituency fiercely clings to the idea that the unique, "lonely warrior" nature of tennis is a critical feature of the game -- no other sport prohibits coaching. Count Wimbledon (among other stakeholders) and many high-profile individuals, including Roger Federer, in this camp. Williams herself is opposed to a change that could prevent a recurrence of last year's debacle.
"One thing I love about tennis is being out there [alone]. It's the one time I don't want to hear anyone tell me anything. You have to figure out. You have to problem-solve," Williams, who denied that she and Mouratoglou ever used hand signals, said after last year's final.
Another large constituency is outraged that the rules against coaching, which are nearly impossible to enforce, are routinely violated and often applied unpredictably. That rubs purists the wrong way, but the remedy -- allowing coaching -- amounts to throwing the baby out with the bathwater.
A player who accepts coaching not only violates the rules but also violates an ethos. That irritates players, as well as pundits and fans, as does the lax application of anti-coaching rules. But interviews with a number of players suggest that illicit coaching might not have much of an impact on match outcomes, or be more than an irritant to those cheated by it.
"I never felt I lost a match because of coaching from the other player's box," John Isner told ESPN.com. "Not one time. It's a bit overblown."
Nor does Isner feel he has ever cheated anyone out of a match, while maintaining that some communication with his team in the player box is the most natural thing in the world. To him, and others, coaching behavior is a matter of shades of gray, not black and white. If someone in his box eagerly makes a gesture indicating that he stay low (something not unlike Mouratoglou's signal), is that really coaching in any meaningful sense?
"One thing I love about tennis is being out there [alone]. It's the one time I don't want to hear anyone tell me anything. You have to figure out. You have to problem-solve." Serena Williams
"Here I am, almost 7 feet tall," He said. "I'm lifting up on my [serve] return when staying low is something I know I need to do. I keep telling myself I need to do it, anyway. Does it matter if I look at my box and my coach is doing that gesture? I'm not even looking there for coaching, really. Just encouragement."
Tennys Sandgren, now ranked No. 72, labored long and hard on the ATP Challenger Tour before making a remarkable breakthrough onto the main tour in 2018. When it comes to scorning the coaching rules, he has seen it all -- including an opponent who was actively counseled through an entire match as he sat during changeovers by a coach seated right behind him.
"I never felt it cost me a match," Sandgren said. "Maybe I looked over, like to ask, 'What's going on here?' But I don't think anyone ever got any golden knowledge that changed the outcome."
On-court coaching was not introduced on the WTA Tour until the twilight years of Chanda Rubin's career. Rubin was accustomed to facing rivals who were sometimes clandestinely coached, but equally used to solving problems on her own. She eschewed on-court coaching and felt no disadvantage when others legitimately availed themselves of it.
"I never felt I lost because of coaching," she said. "Not from the box or on court when it was allowed. My advantage always was thinking through the match."
On-court coaching was introduced by the WTA in 2008 on a trial basis, now in its 11th year. It has been quietly accepted as an addition to the television viewing experience. There have been compelling coaching visits -- Bianca Andreescu's great run at Indian Wells last March produced a few -- along with painfully awkward ones. But the innovation hasn't moved the needle enough in terms of spectator interest to make the ATP Tour or the majors sit up and take notice. It hasn't been a game-changer, not in any sense of the word.
Tournaments that allow coaching don't kick out appreciably different results, and they produce few matches where the impact of a coaching visit is obvious. "Your coach is only there a minute and a half," Rubin said. "That's not enough to change things in a big way. It [the solution] has to be there, inside you."
And there's this: To enable viewers to listen in -- a key element in the decision to allow coaching -- the coaches are miked. That can be problematic for, as Andy Roddick said: "OK, I had a good record against [Tommy] Robredo. If I know I'm going to be playing him for the next 10 years, why would I bring my coach out and discuss my strategy on air?"
Rubin noted that so far, no one has tried to quantify how often coaching visits altered the pattern of a match. It adds to the theory that the coaching rule was adopted mainly for its potential entertainment value. "It's about getting under the hood and hearing what the players and coaches are talking about," Rubin said.
ESPN analyst Pam Shriver is pro-coaching at all tournaments -- partly because she doesn't think the sport can keep it out, and because there's no point having rules you can't or won't enforce. "Guess what? Even with coaching, you have to solve it on your own," she said. "When someone gives advice, it has to be right, you have to filter and execute it. It's still such a lonely thing. Like a pitcher having to close a ninth inning."
Perhaps surprisingly, gender plays no predictable role in attitudes about on-court coaching. Sam Querrey recently told ESPN.com, "I'm probably in a minority on this, but I wish we had it as often as possible."
Rafael Nadal is clear on where he stands. He has pointed out that tennis players pay their coaches all year long but can't call upon them when they're most needed. Well, theoretically, anyway. Nadal received frequent code violations and fines for coaching violations when his uncle and coach commandeered Nadal's guest box.
By contrast, Tennis Channel analyst Tracy Austin, a two-time US Open champion, said of the WTA's on-court coaching rule: "I think it should be taken out altogether. I think that it should be mano a mano, whatever tools I have -- whether it's emotionally or technically or tennis-wise -- versus yours."
Some analysts are uncomfortable with the optics created by the WTA rules. Martina Navratilova told Tennis magazine: "I don't like the fact that it's on the women's tour and not on the men's tour, because then it looks like the women need help and the men don't."
Also, the sight of older men (most pro tour coaches are men, often the fathers of the players in question) gesticulating and lecturing while their young players just sit there, passively listening or staring into space, can be off-putting. "When you see it get contentious, or it brings tears. I don't think that adds to the sport," Rubin said. "It takes away from the idea that this sport is full of strong, independent women who are battling on their own, week-in, week-out."
The WTA model of on-court coaching has a big head start on other approaches but, perhaps significantly, it isn't the one being tried by the USTA at its secondary events. That one allows players to consult with coaches seated courtside when they are on the same side of the court. The only other approach was an ATP experiment at the NextGen Finals in Milan, an exhibition for the best 21-and-under pros. The players there were allowed to communicate with their coaches via headsets -- presumably, perspiration-proof ones.
None of these solutions satisfies all the stakeholders, so it's unlikely any will be adopted soon. And it might turn out that the problem just isn't worth the cost of a solution.