The season-ending Barclays ATP World Tour Finals begin at London's O2 Arena on Monday. Here are five things worth watching out for...
1. Roger Federer back under a roof in London, and attempting to win a record seventh title at the season-ending championships. As anyone who saw the conclusion of this year's Wimbledon final will be able to tell you, Federer is often at his best when he has a roof over his head. So are we about to witness the first indoor London double, with victory under the closed roof of Wimbledon's Centre Court to be followed by a triumph across town at The O2?
Though Federer will be disappointed not to be finishing the year at the top of the rankings - Novak Djokovic is guaranteed to end a second successive season as the world No.1 - the Swiss has the opportunity to win a third straight title at the ATP World Tour Finals.
At the All England Club this summer, Federer won a record seventeenth Grand Slam tournament, and a record-equalling seventh Wimbledon title, putting him level with Pete Sampras. This has also been the year when Federer became the first man in history to spend more than 300 weeks as the world No.1, moving a long way past Sampras on 286 weeks.
Federer's already the most successful player of all time at the season finale - with six titles, he is one ahead of Ivan Lendl and Sampras, who have five each - but he will want to remind everyone that he's as classy in Greenwich as he is on grass.
2. Andy Murray playing in front of his public for the first time since winning a Grand Slam. And what of Ivan Lendl? It will also be intriguing to see whether the British tennis public show something approaching affection for Lendl, for his part in the Murray story. Unloved as a player, but liked and respected as a coach? But don't expect him to smile.
Also don't imagine that Murray will be treating the tournament as he did his return to Dunblane in September, as an opportunity to smile, wave, and sign autographs. If Murray is to achieve his ambition of becoming the first British world No.1, he knows that he needs to have a good tournament in south-east London.
Having only played one round-robin match last season - he then withdrew because of injury - he is well-placed to make a significant improvement to his points tally on the ranking computer.
3. The celebration, and possible last sighting, of Wimbledon doubles champions Jonny Marray and Freddie Nielsen. One of the prizes for Marray and Nielsen, after becoming the first wild card pairing to win the Wimbledon doubles title, was qualification for the year-end championships (the other prizes being the trophy, the cheques and the sense of achievement).
So The O2 won't be celebrating one British Grand Slam champion, but two. But this could be the last tournament that this Anglo-Danish pairing will play together. Marray is casting around for a new regular doubles partner as Nielsen wants to concentrate on his singles career next season.
4. Novak Djokovic wanting to put on a decent show in London. Apart from Roger Federer, the Serbian is the only player in the field to have won the season-ending tournament, as he was the champion in Shanghai four years ago. But, since the tournament was moved to London in 2009, Djokovic hasn't always played his best tennis.
In 2009, he failed to make it out of his group. The following year, he qualified for the semi-finals, but lost heavily to Federer, gathering just five games. And last season, a year which began with a run of 41 victories, he was so tired when he arrived in London that it was hardly that surprising that he only won one match in the group stage.
Djokovic is the first player to end successive seasons as the world No.1 since Federer did so between 2004-7, and he will want to perform at his best at the final event of the year.
5. Juan Martin del Potro to challenge the best? The tournament could go a long way to telling us whether the Argentine, the US Open champion in 2009, could win another slam in 2013, which would turn the Big Four into a Big Five.
Want to see any of this live? There are still tickets available...