(Clarifies Spain's position)
LONDON Feb 2 (Reuters) - Holders Czech Republic showed how tenaciously they will fight to retain the Davis Cup on Saturday, while five-times champions Spain boosted their hopes of avoiding a first-round knockout for the first time since 2006 by winning their doubles rubber against Canada.
Czechs Tomas Berdych and Lukas Rosol won a record-breaking doubles match against Swiss duo Marco Chiudinelli and Stanislas Wawrinka.
Their seven-hour-two-minute victory, including a 24-22 final set, put the Czechs 2-1 ahead in the tie in Geneva and they need to win only one of the two singles rubbers on Sunday.
The Czechs needed 13 match points before the Swiss finally cracked but for France and Serbia things were far more straightforward as they took unassailable 3-0 leads in their matches against Israel and Belgium respectively.
Argentina also clinched a quarter-final berth by taking a 3-0 lead against Germany.
Top seeds Spain, missing top-15 players Rafa Nadal, David Ferrer and Nicolas Almagro and world number 24 Fernando Verdasco, gave themselves a chance of joining them after Marcel Granollers and Marc Lopez produced a gritty five-set win.
Trailing 2-0 after dropping both singles matches on Friday, the Spanish duo overcame Daniel Nestor and Vasek Pospisil 4-6 6-4 6-7 6-3 6-2 to stay alive in the tie.
The Spaniards, however, face a tough task on Sunday with Canada's world number 15 Milos Raonic to play Granollers in the first match of the reverse singles.
Czech Rosol was formerly best known as the man who stunned Nadal at Wimbledon last year but now he has another claim to fame after Saturday's epic doubles win with Berdych.
Their 6-4 5-7 6-4 6-7 24-22 win was achieved despite fierce home support and was sealed by a double fault.
Wawrinka, who lost a five-set epic against Novak Djokovic at the Australian Open, now needs to recover his energy to take on Berdych again in Sunday's first reverse singles.
French duo Julien Benneteau and Michael Llodra thrashed Israel's Dudi Sela and Jonathan Erlich 7-6 6-1 6-0 in Rouen to give France a 3-0 lead.
Jo-Wilfried Tsonga and Richard Gasquet both comfortably won their singles matches on Friday.
World number one Djokovic will be spared more exertion on Sunday after 2010 winners Serbia built up a 3-0 lead against Belgium when Viktor Troicki and Nenad Zimonjic came through in four sets against Steve Darcis and Ruben Bemelmans.
Djokovic, playing his first match since winning the Australian Open for a third consecutive year, crushed Olivier Rochus on Friday on an indoor claycourt in Charleroi.
France, bidding for a 10th Davis Cup title, will face Argentina in the quarter-finals after the South Americans clinched victory with a day to spare against Germany.
David Nalbandian and Horacio Zeballos delighted the Buenos Aires crowd with a 6-1 6-4 5-7 6-2 victory against Christopher Kas and Tobias Kamke.
Kamke stood in for Philipp Kohlschreiber, who retired in the fifth set of Friday's opening singles with a pulled hamstring against Carlos Berlocq.
Germany's captain Carsten Arriens said the home crowd at Parque Roca had been fantastic in their support for Argentina, adding that he would love to have a CD of their chants.
"Argentina will need that to play France," he said.
Serbia will face the United States if they complete victory over Brazil, having forged a 2-0 lead.
Austria kept their tie against Kazakhstan alive as Julian Knowle and Alexander Peya won the doubles to leave the hosts leading 2-1 in Astana. Italy lead Croatia 2-1. (Editing by Tom Pilcher)