* Federer sends shockwaves with last-minute U-turn
* Wawrinka will dig deep after Australian Open win
* Serbia decimated by top players absence
Switzerland's former world number one Roger Federer will join Australian Open champion Stanislas Wawrinka in their Davis Cup first-round tie against Serbia next weekend.
"I can confirm that Roger is in Serbia and will play in the Davis Cup," Swiss Tennis Federation spokeswoman Sandra Perez told Reuters by email on Wednesday.
"He will take part in the press conference tomorrow (Thursday) when the draw takes place," she said.
With Federer renewing his Davis Cup partnership with Wawrinka, the Swiss will start as strong favourites against 2010 winners and 2013 runners-up Serbia, who are missing their top three players including world number two Novak Djokovic.
Federer, the winner of 17 Grand Slam titles on the men's ATP Tour, has never won the Davis Cup and renewing his partnership with Wawrinka should present him with a good chance of adding to his jam-packed trophy cabinet.
The 32-year-old Swiss maestro last played for his country in the 2012 World Group playoff win over the Netherlands and his best result in the competition was reaching the 2003 semi-finals.
Although Wawrinka is likely to be exhausted after his celebrations and a long-haul flight from Melbourne following his win over Spain's world number one Rafa Nadal in Sunday's final, the Swiss should be too strong for a decimated Serbian side.
That is, unless world number two Novak Djokovic follows in Federer's footsteps and makes a last minute U-Turn, having earlier pulled out of the tie to focus on the ATP Tour and his bid to wrestle the top ranking spot back from Nadal.
If there is to be another twist, Djokovic would have to cut short his skiing holiday in the Serbian resort of Mount Kopaonik, where he has been photographed by local media with friends and family.
Serbia will certainly miss the injured Janko Tipsarevic, who has been sidelined with a heel problem since October, and suspended Viktor Troicki who is serving a 12-month doping ban for missing a blood test in April.
The Serbians are relying on the unheralded duo of world number 102 Dusan Lajovic and Filip Krajinovic (280) as the likely singles starters, with Nenad Zimonjic expected to join forces with Ilija Bozoljac in the doubles.
Their coach Bogdan Obradovic thinks Wawrinka's probable exhaustion is Serbia's best chance of springing what would have been upset even with Federer absent.
"It's a predicament not having our best players available but it's also an opportunity to inject some fresh blood into the squad," Obradovic told a news conference in the SPENS Arena prior to breaking news that Federer was on his way to Serbia.
"The atmosphere is great and what we need now is a big fan turnout so that these young lads get the proper support on the big stage. We will do everything we can to win.
"Players like Wawrinka always find a way to dig deep into their resources but despite being up against it, our goal remains to win three points in the tie and advance to the next round."
With Federer now ready to support Wawrinka, who will also be pumped up after winning his first grand slam and rocketing to a career-best world number three, a Serbia win would amount to one of the biggest shocks in Davis Cup history.