PARIS (AFP) - Switzerland's Davis Cup tennis title defence ended with a whimper on Sunday, as Leonardo Mayer ground out the longest win in the tournament's history to keep Argentina's hopes alive.

In searing heat in Buenos Aires, Mayer beat Brazil's Joao Souza 7-6 (7-4), 7-6 (7-5), 5-7, 5-7, 15-13 in six hours and 42 minutes, the second-longest singles match.

Mayer needed 11 match points to close out a first-round epic which surpassed the previous Davis Cup record of six hours 22 minutes for John McEnroe's 1982 win over Mats Wilander.

Mayer found the energy, somehow, to bounce up and down in celebration, but shortly afterwards he was treated for dehydration.

The only longer recorded singles match was the legendary, 11-hour battle between John Isner and Nicolas Mahut at Wimbledon in 2010.

But the marathon win only levelled the tie at 2-2, and Argentina's Federico Delbonis was leading Thomaz Bellucci 6-3 when darkness stopped play in the decisive fifth rubber.

"We both deserved the victory, to me," Souza said. "But one guy had to lose the match. I just want to say congrats to him."

In Liege, Switzerland's title defence proved short-lived as Belgium won 3-2 against a side missing Roger Federer and Stan Wawrinka, who led them to their first Davis Cup crown last year.

Henri Laaksonen forced a fifth rubber for Switzerland with a hard-fought 6-3, 3-6, 3-6, 7-6 (7-5), 6-1 victory over Steve Darcis.

But David Goffin, the world No. 21, easily dispatched 321st-ranked Adrien Bossel 6-4, 6-0, 6-4 in the decisive match.

Belgium next play Canada, who were also pushed to a fifth match in a 3-2 triumph over Japan.

World No. 4 Kei Nishikori did his part with a 3-6, 6-3, 6-4, 2-6, 6-4 victory over Canada's world No. 6 Milos Raonic in the marquee match in Vancouver.

But Vasek Pospisil made short work of Go Soeda 7-5, 6-3, 6-4 to put Canada through as they seek to improve on their best previous Davis Cup showing, a run to the semi-finals in 2013.

Elsewhere, Andy Murray sealed a quarter-final berth for Britain, and Australia and Kazakhstan joined already qualified France and Serbia in the last eight.

Murray, the world No. 5, starred for Britain, claiming victory with a 7-6 (7-4), 6-3, 7-6 (7-4) win over US No. 1 Isner in Glasgow.

It sealed the winning point in an eventual 3-2 triumph and set up a final eight meeting in July against last year's runners-up France, who lost both meaningless reverse singles as they polished off a 3-2 victory over Germany in Frankfurt.

In Ostrava, Bernard Tomic beat Lukas Rosol in straight sets to lead Australia past the Czech Republic and into a quarter-final clash with Kazakhstan.

It was the seventh time in eight Davis Cup encounters that 28-time champions Australia have beaten the Czech Republic.

They'll take on a Kazakhstan team that squeezed past Italy 3-2 in Astana.