“I still have another week where I have to give it all. After, it will be long holidays,” said the 32-year-old Federer after losing to Novak Djokovic 4-6, 6-3, 6-2 in their first meeting this year in the Paris Masters semifinals on Saturday.
The pair was placed in the same group at the season-ending, eight-man finals, which start Monday.
The draw Saturday placed top-ranked Rafael Nadal in Group A alongside fellow Spaniard David Ferrer, Tomas Berdych and Stanislas Wawrinka. Nadal lost to Ferrer in the semifinals in Paris and will have another chance when he plays him again in London on Tuesday.
The finals have a round-robin format, with the top two finishers reaching the semifinals.
Berdych and Wawrinka will open Monday, followed by del Potro playing Gasquet. Wimbledon champion Andy Murray pulled out after having back surgery.
Djokovic won his 16th consecutive match in Paris in the win against Federer. He is the defending champion in London, where he beat Federer in the final last year. Djokovic also won the title in 2008, while Federer has won it a record six times.
FED CUP: In Cagliari, Italy, Roberta Vinci and Sara Errani prevailed in the opening singles for a 2-0 lead Saturday against an understrength Russia and put Italy on the brink of a fourth Fed Cup title.
Vinci, the winner of nine WTA singles titles, overcame a challenge from Alexandra Panova, who has reached only one WTA final.
Vinci rallied from 5-2 down in the second set and saved four match points to win 5-7, 7-5, 8-6 in 3 hours, 13 minutes.
Errani, playing in her second Fed Cup final, overcame newcomer Irina Khromacheva 6-1, 6-4.
TOURNEY OF CHAMPIONS: In Sofia, Bulgaria, top-seeded Simona Halep rallied from a set down to beat Ana Ivanovic 2-6, 6-1, 6-3 and reached the final of the season-ending Tournament of Champions.
Halep, who has won five WTA titles this year, took a 2-1 lead in the opening set, but an inspired Ivanovic broke her serve twice.
Halep took control in the second set with the help of her first serve – only to stumble in the third set. Ivanovic took a 3-0 lead before Halep won six consecutive games.
DAVIS CUP: The International Tennis Federation banned Tunisia from the 2014 Davis Cup on Saturday after one of its players was ordered not to compete against an Israeli opponent at a second-tier tournament in October.
The ITF said in a statement that the Tunisian federation was guilty of “interfering with international sporting practice” when it ordered Malek Jaziri to withdraw from his quarterfinal against Israeli player Amir Weintraub at an ATP Challenger tournament in Tashkent, Uzbekistan.
The ITF said its board voted unanimously to suspend Tunisia from the Davis Cup for one year, with Tunisian member Tarak Cherif recusing himself from the vote.
“There is no room for prejudice of any kind in sport or in society,” ITF President Francesco Ricci Bitti said in the statement. “The ITF Board decided to send a strong message to the Tunisian Tennis Federation that this kind of action will not be tolerated by any of our members. The Board felt that suspension from Davis Cup, a competition that was founded 113 years ago to encourage better understanding through sport, would provide a good lesson for the Federation and a fitting penalty for their unfortunate action.”
Tunisia played in the third-tier Group II of the 2013 Davis Cup, losing to Latvia in the first round.
Jaziri was told in an email from the Tunisian federation that “you are ordered not to play against the Israeli player.” The email was later provided to Tunisia’s state news agency by Jaziri’s brother, Amir.
Arab countries have for the past decades observed to varying degrees boycotts against Israeli athletes in protest over the situation of the Palestinians.