Andy Murray joined Novak Djokovic, Roger Federer and the injury-cursed Rafael Nadal as a Grand Slam title winner in 2012 as the big three became the fab four.

But with the 2013 season beginning just over two weeks' time, the lingering uncertainty over the future of Nadal once again was dominating the build-up to the new campaign.

Nadal clinched a record seventh French Open title in June defeating Djokovic 6-4, 6-3, 2-6, 7-5.

It shattered Djokovic's bid to emulate Don Budge (1938) and Rod Laver (1962 and 1969) by holding all the Grand Slams at once.

Victory in Paris was 26-year-old Nadal's 11th Grand Slam title, but a shock second round Wimbledon loss to Czech Lukas Rosol brought a premature end to the Spaniard's season as another battle against a knee injury meant he missed the Olympics and the US Open.

Nadal is due to return to action at a three-day exhibition event in Abu Dhabi from December 27, but he has already warned against high expectations.

"I don't expect to return and win the Australian Open," he said.

"I want to be 100 percent fit in time for the Monte Carlo Masters and the run-up to the French Open."

Nadal and Djokovic, who was to end 2012 as world number one and be named player of the year, had already set the scene for an enthralling season in a gripping Australian Open final.

Defending champion Djokovic prevailed in an epic five-set contest which clocked in at 5hr 53min -- the longest title match in Grand Slam history.

Djokovic fought back from losing the first set to take a 2-1 lead, but he was then taken to a gripping fifth set by resurgent Nadal before winning 5-7, 6-4, 6-2, 6-7 (5/7), 7-5 for his third consecutive major title.

Although Djokovic missed out in Paris, the Serb still featured in three of the season's four major finals.

His disappointment at his five-set loss to Murray at the US Open would eventually be eased by his capture of the year-ending ATP World Tour Finals title in London.

His 7-6 (8/6), 7-5 victory over Federer put the seal on a memorable year.

"It's been two very successful years," Djokovic said. "I didn't really know how I would follow up after an incredible 2011."

Federer defied the critics who insisted he was past his best by equalling Pete Sampras's record of seven Wimbledon titles with a 4-6, 7-5, 6-3, 6-4 win over Murray.

"It was just a temporary thing," said Federer, after his two and half year wait for another Grand Slam title.

"I believed that maybe down the stretch, like with Andre Agassi (who was 32 when he won the 2003 Australian Open) it's like a steppingstone, a period I have to go through.

The normally granite-faced Murray broke down in tears at the end of the Wimbledon final.

But just weeks later, he used that disappointment to fuel his push to Olympic gold on the same Wimbledon Centre Court with victory over Federer.

Then the Scot finally broke his Grand Slam duck with a 7-6 (12/10), 7-5, 2-6, 3-6, 6-2 win over Djokovic in the US Open final.

That made him Britain's first major champion since Fred Perry claimed his third American title in 1936.

"I'm obviously proud that I managed to achieve it, and don't have to get asked that stupid question again," said Murray who, after losing four previous major finals, had tired of insisting that he would one day break through.

Murray believes he will not be a one-Slam wonder like Andy Roddick who retired from the sport in New York.

The year wasn't without controversies.

Nadal insisted he would never play the Madrid Masters again if organisers continued with their blue clay surface.

At Queen's, fiery Argentine David Nalbandian was disqualified from the final after destroying an advertising hoarding and accidentally injuring a line judge.

French player Gilles Simon reignited the row over equal prize money during Wimbledon, arguing that the men's game was a far more attractive product.

Maria Sharapova begged to disagree and gave Simon an icey rebuke.

"No matter what anyone says, or the criticisms that we get, despite everything else, I'm sure there are a few more people that watch my matches than his," said the Russian.