PARIS - The 2013 Fed Cup World Group gets underway Saturday with the tournament missing marquee names Serena Williams and Maria Sharapova and with a late format tweak aimed at boosting the event’s appeal.Both Williams and Sharapova featured in the 2012 Fed Cup, partly to meet Olympic Games qualifying criteria, but will not be involved when the United States tackle Italy and Russia welcome Japan this weekend. Williams, who has played just six ties since 1999, has a back injury while Sharapova, whose Fed Cup record stretches to a meagre three appearances since her 2008 debut, was left out of the Russian squad.Their absences have cut the number of players from the top 10 competing in the four World Group One ties to just three — number seven Sara Errani of Italy, eighth-ranked Petra Kvitova of the Czech Republic and number nine Samantha Stosur of Australia. Wary of the growing demands placed on time and physical endurance by the professional tour, the International Tennis Federation (ITF) announced on Thursday changes concerning dead rubbers in the tournament.Under the new policy, if a tie is decided after the third singles rubber, the fourth singles rubber will not be played and the dead doubles rubber will be played instead. However if the tie is only decided after the fourth singles rubber, the dead doubles rubber will still be played with a match tiebreak (first to 10 points) replacing the third set.“The enhancement of the dead rubber policy came in response to requests from players, captains and National Associations following its successful introduction in Davis Cup,” said ITF executive vice-president Juan Margets. “This is part of the ITF’s continued effort to make Fed Cup more player friendly, while maintaining a good spectator experience on the Sunday.”Former Wimbledon champion Kvitova leads defending champions Czech Republic against Australia in Ostrava where she will be playing her 14th Fed Cup tie since 2007. However, she has struggled this season, a shock second round exit at the Australian Open followed by a quarter-final loss in Paris last week where she was second seed.“My results are not exactly what I want them to be, but I still believe it will be OK. I know I can play tennis, and I like Fed Cup,” said the 22-year-old. In the absence of the Williams sisters, as well as Australian Open semi-finalist Sloane Stephens, the 17-time champions US will be led by world number 21 Varvara Lepchencko when they face Italy in Rimini.Italy, with Errani and world number 16 Roberta Vinci likely to play singles and doubles, beat the US in the 2009 and 2010 finals. Even without Sharapova, Russia, the four-time winners, should be too strong for Japan in Moscow. Maria Kirilenko, at 13, Ekaterina Makarova, the world number 20, Anastasia Pavlyuchenkova, the 31st-ranked player and number 32 Elena Vesnina, are all higher up the WTA pecking order than Japan’s top singles player Ayumi Morita, the world 57. In Nis, 2012 runners-up Serbia, who are likely to be without world number 14 and former French Open champion Ana Ivanovic with a shoulder injury, tackle Slovakia.Fixtures: World Group IAt OstravaCzech Republic v AustraliaAt RiminiItaly v USAAt MoscowRussia v JapanAt NisSerbia v SlovakiaWorld Group IIAt BerneSwitzerland v BelgiumAt Buenos AiresArgentina v SwedenAt AlicanteSpain v UkraineAt LimogesFrance v Germany