Tatiana Golovin is serving to Jie Zheng at 2-2 and deuce in the third set of their quarter-final in the Nasdaq-100 Open. Zheng hits what she thinks is a forehand winner, only for a line judge to call it out. The Chinese player tells the umpire Adel Aref that she wants to challenge the call.
Aref's microphone relays the message to Paul Hawkins in a booth above the court. "Drama, drama," says one of the two technicians sitting alongside the 31-year-old British scientist, whose Hawk-Eye computer system is being used here to decide line calls at a tour event for the first time.
All eyes in the booth, including those of Lynn Welch, a tour official, are on a small screen that shows in graphic form the ball's flight path and where it has just landed. Hawk-Eye confirms the call was correct. The same sequence is shown on the large on-court video screen to players, officials and spectators. Zheng, waiting maybe in hope rather than expectation, bows her head. The whole process has taken less than 10 seconds.
Critics had suggested that Hawk-Eye would slow the game down. The consensus now is that it has speeded it up. Whereas players might previously have berated the line judge and umpire, the challenge process not only takes the heat out of the situation - it is far quicker. No player has yet screamed at Hawk-Eye: "You cannot be serious!"
Challenges can be made only on the last shot of a rally; by the start of play yesterday no player had stopped to challenge a call. Players can make two challenges per set plus one in a tie-break. They lose a challenge if wrong but can keep making them if right.
Amélie Mauresmo still has reservations - "The procedure is a little bit too long, with the umpire saying, 'Miss Whatever is challenging this line', or whatever," she said - but others believe that Hawk-Eye is actually too quick.
"We're in the entertainment business," Tim Henman said. "It's a great concept. The crowd are shouting: 'Challenge it, challenge it!' I think we've got to milk it a bit more on the big screen. In cricket, when they've got a run out or something, the thing comes spinning and you're made to wait."
Hawkins, who has already tweaked the graphics so that the "in" or "out" verdict is displayed at the end of the sequence, creating more suspense, believes that Hawk-Eye has shown what a good job officials do. Before the start of play yesterday there had been 132 challenges (66 by men and 66 by women), of which only 33 per cent had been successful. Men had a 39 per cent success rate, women 27 per cent.
Hawk-Eye itself, which makes more than a billion calculations during a typical rally, has been more successful. By yesterday morning its eight cameras had tracked more than 10,000 shots and failed just once, when a visiting news camera crew in the booth accidentally knocked out a power cable.
Andy Roddick believes that Hawk-Eye's sheer presence has improved line-calling. "Officials now have to be accountable," he said. "That used to drive me up the wall because they could make a decision and not really care about it. At least they look stupid in front of 15,000 people now if they make the wrong call."
Henman says the players are just as likely to look foolish. "I've definitely been able to bitch and moan about calls for a good couple of games," he said. "Here, if there's an instance where you're uncertain, ask the question and are proved wrong, you look like a bit of an idiot. But you certainly don't dwell on it."
James Blake welcomes the fact that players are showing officials more respect. "I don't get yelled at every time I miss a forehand, and they shouldn't get yelled at every time they miss a call," he said. "Maybe we'll be humbled a little bit. I think a lot of us need that."
However, some players are concerned that umpires are less inclined to overrule bad calls. Lleyton Hewitt says it is hard to see where a ball lands at the far end of the court, in which case he wants umpires to be prepared to overrule. Maria Sharapova agrees. "In crucial, crucial situations in a match, it can be a little frustrating," she said. "The umpires aren't making as many overrules as they were before. They want us to challenge it if we feel the call is wrong. Sometimes I feel that if they really saw it clearly I'd rather they overruled it than having me challenge it. Then the other girl can challenge it if she feels the overrule was wrong."
Umpires themselves can ask for Hawk-Eye's verdict only if a line judge has been unsighted, but none had done so by yesterday morning. Butch Bucholz, the tournament chairman here, would like umpires to be able to consult Hawk-Eye if a player has run out of challenges, but others suggest this would simply take us back to square one, with players regularly questioning calls with the umpire.
So far only the US Open and Australian Open have said they will also use video technology, though officials from the Stella Artois tournament were here looking at the system and Wimbledon plans to test it at this year's championships.
Hawk-Eye is used only on the main court here and cost more than $100,000 (about £57,000) to install, although it was already being used for television and the only additional cost for the tournament was $20,000 (£11,000) to bring in six technicians rather than two. Hawkins says the on-court video screens are the major cost, though he believes that they can pay their own way through sponsorship. He is also working on a scaled-down version, without on-screen displays, which, for example, the Grand Slam tournaments might use on the outside courts.Reuse content