Djokovic, Murray and Nadal all have other agendas

The Davis Cup quarterfinals take place this weekend - minus the superstar drawing power of Novak Djokovic and Andy Murray and overshadowed by Rafael Nadal's last-ditch effort to get to the Rio Olympics.

World No 1 Djokovic and newly crowned Wimbledon champion Murray were expected to play in the quarterfinal between Serbia and defending champion Britain, but Djokovic pulled out of the tie after his third-round Wimbledon exit to America's Sam Querrey - the Serb's earliest loss at a Grand Slam event in nine years.

Murray, the world No 2, is still officially listed on the British team for the Friday-Sunday tie on outdoor clay in Belgrade, but the 29-year-old is expected to watch from the sidelines as he rests ahead of a packed summer schedule that includes next month's Olympics as well as the US Open.

"Andy has to look after his body and his mind. He's got his eyes set on getting some rest and really making a big push for the Olympics, US Open and beyond," Britain team captain Leon Smith told the BBC.

The British challenge will be led instead by world No 67 Kyle Edmund and 240th-ranked James Ward.

In the absence of Djokovic and Viktor Troicki, world No 81 Dusan Lajovic will lead 2010 champion Serbia.

Meanwhile, 14-time major winner Nadal and his Spanish team do not feature in the World Group quarterfinals, but the 30-year-old still faces a key weekend as he hears whether or not the International Tennis Federation (ITF) will give him the go-ahead to take part in Rio.

Nadal hasn't traveled to Romania for the Euro/Africa zone playoff as he continues to recover from a wrist injury that forced his withdrawal from the French Open and caused him to miss Wimbledon.

Nadal is anxious to play in Rio after being unable to defend his gold medal at London in 2012 due to a knee injury, but he hasn't fulfilled the qualifying criteria.

In other quarterfinals this weekend, Italy hosts Argentina in Pesaro.

Juan Martin del Potro, the 2009 US Open winner, is back on the Argentina squad after a four-year absence. Federico Delbonis, the world No 40, is the South Americans' top player while Fabio Fognini, ranked 36, leads Italy's challenge.

In Trinec, the Czech Republic, which won the championship in 2012 and 2013, squares off with nine-time winner France, which last won in 2001.

The Czechs will miss their No 1, eighth-ranked Wimbledon semifinalist Tomas Berdych, while France will be led by 10th-ranked Jo-Wilfried Tsonga.

France can also call upon Wimbledon doubles champions Nicolas Mahut and Pierre-Hugues Herbert.

The weekend's remaining quarterfinal sees 32-time champion United States host Croatia in Portland, Oregon. Both sides boast two top-20 players - John Isner for the home side and former US Open champion Marin Cilic for 2005 champion Croatia.

Croatia has won all three of the nations' previous ties, with Cilic also starring in the most recent encounter, a quarterfinal in 2009.

Quarterfinals

At Belgrade (clay, outdoor): Serbia vs Britain

At Pesaro (clay, outdoor): Italy vs Argentina

At Trinec (hard, indoor): Czech Republic vs France

At Portland (hard, outdoor): United States vs Croatia