Roger Federer has done a U-turn and decided to join the new Australian Open tennis champion Stanislas Wawrinka in Switzerland's Davis Cup team for this weekend's first round tie in Serbia.
Federer has made a late decision to play the tie despite Serbia being without their top three players Novak Djokovic, Janko Tipsarevic and Viktor Troicki.
The 32-year-old last played for his country in a World Group playoff against the Netherlands in 2012.
