Lille - Roger Federer, whose back injury has cast serious doubts over his Davis Cup final spot, practiced for the first time on Wednesday in a timely boost for the Swiss team ahead of their showdown against France.
The 17-time major winner, who has never won the Davis Cup, injured his back playing in the semi-finals of the World Tour Finals in London on Saturday and had not hit a ball until Wednesday.
He won the gruelling three-set marathon in London against Swiss team-mate Stan Wawrinka after saving four match points, but paid a hefty price for his efforts and was unable the following day to take on Novak Djokovic in the final.
On Wednesday evening, the 33-year-old Federer hit with Switzerland's number four player Michael Lammer on the clay courts of the Pierre-Mauroy de Villeneuve-d'Ascq stadium.
Federer spent 15 minutes hitting from the back of the court, playing forehands and backhands before switching to volleying, showing few signs of his back problem.
He then switched to serving although observers at the session said that his 20 service actions were not at full pace.
Federer did have an early afternoon slot available on Wednesday but did not appear, leaving Wawrinka and the other Swiss players to practise by themselves.
Tuesday evening Federer said he was unable to ascertain just what his chances were of being able to play on Friday and was taking it day by day.
"I'm making some progress. But I know I don't have a month ahead of me to get better. I need to get better quickly. I'm trying whatever I can," he said.
The problem for the Swiss is that although Wawrinka, at fourth in the world, is comfortably ranked above all the French players, after him the fall-off in the Swiss team is steep with Marco Chiudinelli 212th and Lammer 508th.
Without Federer, their chances of winning the Davis Cup for the first time look slim, with the French boasting a strength-in-depth line-up of Jo-Wilfried Tsonga, Gael Monfils, Richard Gasquet and Julien Benneteau.
The team line-ups for the Friday-Sunday finals will be revealed at 13:30 (SA time) on Thursday.