Tennis fans might well feel confused when they look through this week's results from the sport.
For the first time in more than 30 years the tennis scoring system has been changed, in a controversial experiment with the format of men's doubles.
Reaction to the ATP's tinkering has been mixed.
While the men's tour governing body says the changes will revive doubles, players are worried they will erode the discipline's standing in a sport already dominated by singles.
In tournaments in Beijing and Bucharest last month doubles sets were played to six with a tiebreak at 5-5 and no advantage games; this week in Metz and Tokyo sets are to five with a tiebreak at 4-4, also with no advantage games.
A third variation will feature no third sets, but a match tiebreak played to 10 points.
On Wednesday, French pair Fabrice Santoro and Michael Llodra, the top seeds at the Open de Moselle in Metz, beat compatriots Paul-Henri Mathieu and Gael Monfils by the novel scoreline of 3-5, 5-4, 5-4.
Santoro, one of the world's leading doubles players, said he is uncomfortable with the new scoring system.
"It's a bit early to come up with conclusions about it but I don't think I am for it right now," the 32-year-old former Australian Open doubles champion told reporters on Wednesday.
"To me, the set to five and the "no-ad" are too much of a change. I want to say that it's the no ad point that bothers me the most."
POSITIVE FEEDBACK
Under the new rules, when a game reaches deuce a sudden-death point is played with the receiving team electing who will return serve.
The ATP hopes to decide on the best scoring system by the time of the Masters Cup in Shanghai next month.
It says there has been some positive feedback so far, from players, tournament organisers and spectators.
"When you make changes you are never going to get 100 percent support," the ATP's communications director Nicola Arzani said on Thursday.
"Some of the traditionalists don't like it, but others think it's more exciting. The shorter format means more doubles matches are scheduled for show courts and that's positive."
World number two Rafael Nadal has welcomed the changes, and other players believe they add excitement.
"I tried it in Bucharest two weeks ago," Mathieu said this week in Metz. "It's a little weird because it is new but I like it and I think it's more fun and attractive to the public.
"I definitely think more singles players will be willing to play more doubles."
While players generally seem happy to try the new scoring, proposed changes to the qualification process for doubles at tour events from 2008 are likely to be more problematic.
At the US Open, American leading doubles specialists, including twins Bob and Mike Bryan, filed a lawsuit seeking to stop the ATP implementing the changes.
SINGLES RANKINGS
By 2008 the ATP wants to base qualification for doubles on a player's singles ranking, a change that would exclude the Bryans, who were the top-ranked team in 2003 and most of 2005, and Wimbledon doubles champion Stephen Huss.
Zimbabwean pair Wayne Black and Kevin Ullyett, this year's Australian Open champions, do not even have singles rankings.
"Our backs are against the wall right now. If we don't unite, there might not be a game of doubles," Mike Bryan said at a news conference during the US Open.
Santoro, one of the few players to combine a successful singles and doubles career, sympathises.
"It's true that the best doubles players are not the most famous, but it is not their fault, they are trying to play good tennis, win tournaments," he said.
"If they are not as famous it could be in part because the ATP hasn't been promoting them well.
"I am putting myself in their position. Right now it's really hard, they show up at a tournament and people are trying to put them aside while they are only trying to do their job."
The ATP said it is optimistic that an agreement could be reached to suit all sides.
"I believe that we want the same result [as the players], we don't want to kill doubles, we need to work together," said Arzani.
"We will sit down and work out our differences. It's disappointing that they took out a lawsuit, but we have made progress and are confident we can work together."
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