Serbia reached the Davis Cup quarter-finals to set up a possible interesting clash between Grand Slam heavyweights Novak Djokovic and Rafael Nadal while champions Argentina stayed alive.

Serbia, the 2010 champions, took an unassailable 3-0 lead over Russia on Saturday in their World Group opener in Nis when 40-year-old Nenad Zimonjic and Viktor Troicki downed Andrey Kuznetsov and Konstantin Kravchuk 6-3, 7-6 (7/3), 6-7 (5/7), 6-4.

On Friday, Troicki beat Karen Khachanov 6-4, 6-7 (3/7), 6-3, 1-6, 7-6 (8/6) in the opening singles before Djokovic made it 2-0 when Daniil Medvedev retired with cramps in the fourth set allowing the 12-time major winner to claim a 3-6, 6-4, 6-1, 1-0 win.

"I have to congratulate Viktor for an excellent match after spending five hours on court Friday," said Zimonjic, the Serbia captain.

"It was a massive challenge even though he's one of the fittest players on tour."

Djokovic could face Nadal in the last eight in April should five-time champions Spain see off Croatia in Osijek.

Nadal was sitting out the trip to Croatia after reaching the Australian Open final last weekend but would be certain to return to face a Djokovic-inspired Serbia.

However, Croatia were trying their best to ignore the script when they took a 2-1 lead over the Spaniards thanks to Marin Draganja and Nikola Mektic carving out a 6-7, (6/8), 7-6 (9/7), 7-6 (7/5), 2-6, 6-4 win over Feliciano Lopez and Marc Lopez, the French Open champions.

Croatia, playing without top star Marin Cilic, saw world number 223 Franko Skugor unexpectedly defeat 26th-ranked Pablo Carreno Busta on Friday before world number 16 Roberto Bautista Agut levelled the tie overnight by beating Davis Cup debutant Ante Pavic, the world number 486.

Meanwhile, Carlos Berlocq and Leonardo Mayer kept defending champions Argentina in their tie against Italy in Buenos Aires with a marathon 6-3, 6-3, 4-6, 2-6, 7-6 (9/7) win over Simone Bolelli and Fabio Fognini.

That made the overall score 2-1 after Paolo Lorenzi and Andreas Seppi had won the opening day singles against an Argentina team missing Juan Martin del Potro and Federico Delbonis, the stars of their 2016 final triumph over Croatia.

On Saturday, Berlocq and Mayer needed six match points to secure their win.

Australia, the 28-time champions, completed a 3-0 drubbing of the Czech Republic in Melbourne when John Peers and Sam Groth breezed past Jiri Vesely and Jan Satral, 6-3, 6-2, 6-2.

Australia, captained by Lleyton Hewitt, will now host the United States in the quarter-finals on April 7-9. The US, the 32-time champions, completed a 3-0 win over Switzerland in Birmingham, Alabama, on Saturday when Steve Johnson and Jack Sock beat Henri Laaksonen and Adrien Bossel 7-6 (7/3), 6-3, 7-6 (7/5).

Against a Swiss side missing Roger Federer and Stan Wawrinka, world number 20 Sock got the United States off to a fast start on Friday, seeing off world number 146 Marco Chiudinelli 6-4, 6-3, 6-1.

John Isner, ranked 23rd, had to work a little harder for a 4-6, 6-2, 6-2, 7-6 (7/1) victory over Laaksonen, ranked 127th in the world.

Nine-time champions France wrapped up a 3-0 victory against Japan after Wimbledon winners Pierre-Hugues Herbert and Nicolas Mahut brushed aside Yuichi Sugita and Yasutaka Uchiyama 6-3, 6-4, 6-4.

France will play either Canada of Britain for a place in the last eight.

In Ottawa, Jamie Murray and Dominic Inglot defeated 44-year-old Daniel Nestor and Vasek Pospisil 7-6 (7/1), 6-7 (3/7), 7-6 (7/3), 6-3 as Britain took a 2-1 lead.

The two countries were locked 1-1 overnight after Dan Evans, his country's top player in the absence of world number one Andy Murray, beat 17-year-old Denis Shapovalov in straight sets.

Pospisil pulled Canada — missing world number four Milos Raonic — level with a 6-4, 6-1, 7-6 (7/3) victory over Kyle Edmund.

In Frankfurt, Belgium were 2-1 ahead of Germany after Ruben Bemelmans and Joris De Loore sealed a 6-3, 7-6 (7/4), 4-6, 4-6, 6-3 win over brothers Alexander and Mischa Zverev.

The winners will face either Argentina or Italy in the last eight.

The reverse singles in all eight World Group ties take place on Sunday.