Replay Challenge Becomes a Useful Player Tactic
By GREG BISHOP
Published: September 10, 2009
Serena Williams, watching
a line call replay, is the
women’s challenge master,
winning 57.9 percent of
challenges this season.
Several times each match, fans in the main stadiums at the United States Open turn as one toward giant video screens, which display decisions when players challenge calls. Fans trace the trajectory of an animated tennis ball and clap in rhythm, oohing and aahing at challenges both affirmed and denied.
When tennis introduced its challenge system three years ago at this tournament, it was such a novelty that it took nearly two days for a single player to issue a challenge. Now, the system is part of the routine, with over 500 challenges already issued at this Open.
As with any system in sports, players and coaches have tried to exploit it for strategic gain. No longer are challenges as clear as what they were intended for: determining if a tennis ball landed in, or out.
“It’s the best thing introduced into tennis since the tiebreak,” said Larry Stefanki, a former player and longtime coach. “I wish they had it when John McEnroe was playing.”
On the surface, replay challenges seem simple. Players are allotted three per set and an additional one each tiebreak.
The system works in ways different from other sports. Unlike in the National Football League, a decision to challenge a call is decided in seconds rather than in minutes. And it is decided not by a coach but by a player who is more emotionally invested in the outcome.
And so strategies have been developed, minor tweaks that can have major impacts.
Over the years players have learned to save challenges for late in the set, rather than risk running out of them before they really need one. In a recent tournament, Fernando González chose not to challenge a close call against Roger Federer, despite leading, 6-4, in the decisive tiebreak. He later said that he did not want to break his mojo.
Others make challenges more liberally — “They’re more delusional,” Stefanki said — preferring to use them instead of lose them. This often happens late in sets, when points are more important, as when Juan Martín del Potro challenged his own serve in a third-round singles match. Having not played the return, he was hoping it was out. (It was not.)
Beyond the frequency of challenges, players use them to catch their breath or disrupt the rhythm of an opponent. They are supposed to signal challenges immediately, but since there is no exact time limit — the chair umpire makes a judgment call — some players walk around for 15 to 20 seconds, trying to spot the mark before they challenge.
Stefanki said ATP World Tour tournaments were less lenient in terms of time, but in Grand Slam tournaments, with umpires drawn from the International Tennis Federation, players were allowed more. In his fourth-round match, Andy Murray argued a challenge by Marin Cilic, who missed a return before challenging whether the ball he hit was out.
“There has to be some sort of limit,” Stefanki said. “It has to be a spontaneous thing, or that’s abusing what the system is there for.”
Sometimes players use no strategy at all, challenging for frustration’s sake. Maria Sharapova did this repeatedly in her third-round loss to Melanie Oudin, leaving her without challenges later on critical points.
At other times, players look into the stands for advice from coaches. Stefanki said he holds aloft an index finger for Andy Roddick to indicate a call should be challenged, even though he said there should be a rule against it. Magnus Norman said he signals Robin Soderling. Of course, this can lead to disagreements between players and coaches, as happened recently when Roddick told Stefanki his eyes were going at age 52.
“Sometimes Robin is angry with me afterward,” Norman said. “But it’s easier for me to see, and I contend that I’m right more than I’m wrong.”
The challenge system sits high above Arthur Ashe Stadium, up an elevator, down a hallway, across from a fire hose. The door outside reads: Room 7003, Player Challenge Booth. Inside, cables snake across the room, around computer monitors, laptops and Luke Aggas, an employee at Hawk-Eye.
This system is the brainchild of Paul Hawkins, who holds a doctorate in artificial intelligence and developed Hawk-Eye, at first for cricket, with technology used for tracking military missiles. This year Hawk-Eye was installed on the Grandstand Court, in addition to Ashe and Louis Armstrong Stadiums.
Four people work in the booth. One monitors the 10 cameras on each court that pinpoint where balls landed within three millimeters, according to Hawk-Eye. Another logs the points. A third controls the replays seen by fans. A tournament official provides supervision.
Norman said players still complained that the system was not 100 percent accurate. But of the more than 500 challenges made in this tournament, Aggas said, the system’s data showed only one call it was “unhappy” with. Aggas added that the system had reaffirmed faith in lines people and chair umpires, because it showed they were often correct.
In fact, through Tuesday, 512 challenges had been issued in this Open. Players proved correct on 136 of them, about 26.6 percent of the time, which is about the average, or slightly lower than the average, in most tournaments. This may seem like a paltry percentage, but 136 overturned calls remains a significant number.
Among players, Novak Djokovic remains the men’s challenge master, winning 55 percent of the time this season and 53 percent in his career. Serena Williams leads the WTA at 57.9 percent this season. These numbers stand in stark contrast to someone like Michael Llodra, who has been correct on three of his 23 challenges in 2009.
Challenge victories do not equate to tournament success. For every Djokovic, ranked fourth, there is someone like Andy Murray (ranked second, 27 percent career challenge success rate) or Gael Monfils (13th, 24 percent). For every Williams, there is a Dinara Safina, ranked first with a 33 percent success rate this season.
The strangest case of all is Federer, who has long criticized the system, believing it puts the onus on players instead of on chair umpires. Federer makes challenges constantly, often for what seems like no reason, or with disdain for the entire process. Stefanki said coaches joke in the locker room that if someone like Federer misses by six inches, he should be penalized two points.
“Doesn’t matter what I think about it,” Federer said this week.
But players and coaches believe the system has changed tennis, mostly for the better. Hawk-Eye has helped to educate, by showing that marks left by balls do not always show exactly where they landed.
Hawk-Eye has also helped to decide sets, matches, even tournaments, as when Djokovic correctly challenged a call on match point to win an ATP tournament in Dubai, or when Roddick had a call overturned in London, one that would have left him facing a match point.
The system is so ingrained, in fact, that it has led to debates over whether it provides an advantage for the best players, who spend more time on show courts and have grown accustomed to the way it works. Aggas agreed with that sentiment, but said the overall stadium court benefits were more pronounced.
“It has been revolutionary,” said Darren Cahill, the former pro and ESPN commentator. “You’ve seen matches turned around, less temper tantrums, more focus on the tennis instead of disputes, and more excitement for the fans.”
Some people believe technology will someday replace human judgment.
“Pretty soon, they’re going to get rid of all the linesmen,” Stefanki said. “I could see it happening in the next five years. I might not be as traditional as some, but I’d rather have technology than a linesperson with two-inch-thick glasses making the call anyway.”