Perth: Star players Roger Federer and Angelique Kerber have cautiously welcomed new tie-break rules for the deciding set at the Australian Open.
The year's opening Grand Slam, starting January 14, will for the first time feature an extended tie-break in the final set when the score reaches 6-6, rather than a traditional full set.
To win the decisive tie-break, a player will need to be the first to 10 with an advantage of at least two points.
The move means all four Slams now use different rules, with only the French Open holding off from introducing a tie-break in the decider.
Speaking at the Hopman Cup in Perth this week, Federer -- who said he had been asked for his opinion on the change by tournament officials -- admitted marathon final sets would be missed by some.
"We will miss the 70-68 in the fifth, so that's a pity," he said, referring to the famous final-set marathon between John Isner and Nicolas Mahut at Wimbledon in 2010.
But Federer, aiming for his third successive Australian Open title and seventh overall, said he was personally "a bit torn" between the options.
"I am okay with any format really," he said. "Thing is, when it goes to six-all in the fifth, you've had plenty of chances to win it, or lose it, so from that standpoint how it ends is secondary in my opinion."
Kerber -- who has based her game on superior physical fitness -- suggested her advantage could be diluted by shortened deciders in Melbourne, where she won her first Slam in 2016.
"I like physical matches and if you come here to Australia you have be really fit," she said. "With the weather, the conditions, it's really hot and humid and you have to ready for that.
"I have no idea if I like (the new rule) or not, we will see."
But the German world No.2, who was beaten 9-7 in the deciding set of last year's Australian Open semifinal by Simona Halep, also said she could see both sides of the debate.
"It might be easier because you can save energy, on the other side it is a tradition to play the advantage set," she said.
"Let's see how it works this year."
Among the other Slams, Wimbledon will use final set tie-breaks at 12-12 starting from 2019, the US Open plays a traditional tie-break at 6-6 and the French Open does not use a final set tie-break.
"The funny thing is we have four different formats in four Slams, so it is important to remind yourself what's going on and which one it is," said Federer.