Switzerland's hopes of a first ever Davis Cup win lay in the balance on Monday as the team awaited word on just how badly Roger Federer had injured his back ahead of this week's final against France in Lille and faced reports of a possible dispute in the locker-room between Federer and his teammate Stanislas Wawrinka.
The 17-time Grand Slam winner shocked thousands of fans and his opponent Novak Djokovic in London Sunday evening when he withdrew from the final of the season-ending World Tour Championship saying he was not match fit. (Also read: Federer a doubt for Davis Cup final, says Djokovic)
Ironically the player who helped inflict the back injury on the Swiss great was none other than Davis Cup teammate and close friend Stan Wawrinka.
The two played a thrilling, but punishing semi-final on Saturday evening which Federer, 33, won in three gruelling sets, saving four match points along the way.
Swiss press reports said that Wawrinka had been irked by someone sitting in Federer's box with suggestions it could have been his wife Mirka.
Former great and now television commentator John McEnroe, meanwhile, spoke of the two Swiss players having a long and tense discussion in the locker-room afterwards.
Whatever the truth was there, a Federer withdrawal from the Lille contest would be a huge and potentially lethal body blow to Swiss hopes.
Wawrinka at fourth is comfortably ranked above all the French players, but after him the fall off in the Swiss team is steep with Marco Chiudinelli 212th and Michael Lammer 508th.
Federer has a history of back pain, but until last weekend he had been injury-free throughout a season in which he has played some superb tennis despite failing to add to his Grand Slam title haul.
He is hoping that the back spasms he felt will clear over the next couple of days, allowing him to be able to begin adapting to the indoor claycourt that France as hosts have chosen for the final.
There was some astonishment in the French press over how hard Federer and Wawrinka had gone at it in London, knowing that the Davis Cup final was only a few days away.
Australian Open winner Wawrinka admitted that he could suffer psychologically and physically from the heart-breaking loss and there were unconfirmed reports of some friction between the two after the match.
In stark contrast it was all plain sailing for the French who are seeking a 10th Davis Cup title in all and a first since 2001.
Captain Arnaud Clement cloistered his team of Jo-Wilfried Tsonga, Gael Monfils, Richard Gasquet and reserve Gilles Simon in Bordeaux where they honed their claycourt skills away from prying eyes.
Doubles specialist Julien Benneteau, who was playing in the doubles in London, was to link up with them in Lille.
Coach Lionel Roux said the team would not be distracted by the doubts surrounding Federer's participation.
"I don't think Roger's injury is too serious," he said. "If he really can't play in the Davis Cup it would be very sad. But in my view it was just preventative.
"Looking at the TV footage of his semi-final I saw no signs of him being badly injured. He was struggling a bit only because it had been such a tough match.
"All the players are carrying injuries by the end of the season and we know that Roger has had problems with his back before.
"But he is a real pro and he simply weighed up the pros and the cons and decided against playing the final."
(With Agency Inputs)