By Martyn Herman
LONDON (Reuters) - For Andy Murray 2012 marked a golden milestone, for Novak Djokovic the year was an emphatic reminder of his status as the world's best male player, and for Roger Federer and his army of fans it was proof that the old master's magic still sparkles.
Serena Williams used the second half of the year to demonstrate that she continues to be head and shoulders above her rivals in the women's game, whatever the rankings suggest.
Of the sport's marquee names, only Rafa Nadal will reflect on the past year with regret after six months out with a knee injury, and all eyes will be studying the 11-times grand-slam winner's form once the new season swings into action.
Nadal, one of four different winners of the men's grand-slam titles this year, has not played a match since a shock Wimbledon defeat by Lukas Rosol.
He hopes to return at the Australian Open although he has sensibly lowered expectations of an immediate impact.
In any other era the absence of a player of Nadal's caliber would be an impossible void to fill yet such is the quality at the top of the men's game that the Mallorcan's extended lay-off merely took a little gloss off what was otherwise a vintage year.
Murray began it with a new coach in Ivan Lendl but still without a grand-slam title on his CV having lost in his first three major finals without taking a set.
The Scot became Britain's first male Wimbledon singles finalist since Bunny Austin in 1938 but Federer's grasscourt brilliance deprived Murray of the title.
Three weeks later Murray returned to the All England Club lawns like a man on a mission and he rode a wave of national euphoria to thrash Federer in the Olympic singles final.
Fuelled with belief, Murray then strode into New York and when a fifth shot at a grand-slam final duly arrived he rose to the occasion to beat Djokovic in a five-set epic.
It was a setback for Djokovic but the Serbian, who began the year by beating Nadal to retain the Australian Open title in the longest-ever men's grand-slam final, finished it off as year-end world number one for the second season running.
"Considering the circumstances that I had to face on and off the court, expectations, all these things, I believe that this year has been even more successful for me," Djokovic, who won three major titles in 2011, said after beating Federer to win the ATP Tour Finals at London's 02 Arena.
Though Federer's year ended in defeat, the 31-year-old Swiss will look back on 2012 with pride.
A record-equaling seventh Wimbledon title took his grand-slam haul to 17 and propelled him back to the top of the world rankings long enough to surpass Pete Sampras's record of 286 weeks as number one.
The father-of-two is expected to scale back his schedule in 2013 but will still be a force to be reckoned with when the big prizes are up for grabs.
"I think it's been a fantastic season to be part of," Federer said. "Four different grand-slam champs. Then having the Olympics, as well, was obviously very unique."
Fellow 31-year-old Serena Williams had a relatively slow start to the year but after losing in the first round of the French Open to Virginie Razzano she was unstoppable.
The American won a fifth Wimbledon title, completing a golden slam by winning the Olympic singles gold in London, as well as the doubles with sister Venus, and a fourth U.S. Open title and capped the year by not dropping a set at the WTA finals in Istanbul.
Belarus's Victoria Azarenka ended the year as a worthy number one having captured the Australian Open and five other titles, while Maria Sharapova completed a career grand slam at the French Open but Williams was rightly named WTA Player of the Year.
After her battles with serious injury and health problems in recent years, Williams appears as hungry as ever and will be the woman to beat when the new season begins at the end of December.
"It's amazing that I'm still considered like one of the top players to beat. For me it's the ultimate honor and the ultimate compliment," Williams said in Istanbul before suggesting that the best might still be to come.
"I definitely think I can improve," said the 15-times major winner. "The day I feel that I can't improve, I think that's the day I should probably hang up my racquet."
Should Nadal return to his full force in 2013 the top four of the men's game looks set in stone, although several players have shown in 2012 that they can shake up the top order.
Juan Martin del Potro enjoyed an injury-free year and got back to the form that saw him win the 2009 U.S. Open final while Canada's Milos Raonic, Japan's Kei Nishikori and Poland's Jerzy Janowicz will be worth watching.
On the women's side, 2011 Wimbledon winner Petra Kvitova looks the most likely to threaten the leading trio, although consistency remains her undoing.
In team tennis the Czech Republic dominated.
Their men beat Spain to win the Davis Cup for the first time as an independent nation - reward for Tomas Berdych, one of the most consistent performers on the tour throughout the year - while the women retained the Fed Cup, beating Serbia.
(Editing by Clare Fallon)