text: Meanwhile, the big four of Djokovic, Federer, Nadal and Murray show no signs yet of retiring, while others such as Wawrinka, Berdych, and Nishikori also provide competition and excitement for fans and backers of the sport.
  So it may come as something of a surprise to learn that ATP chief executive Chris Kermode, the man behind the continued upwards trajectory, is about to launch a major review looking ahead to what direction men's tennis should take from 2018 onwards.
  "We will start the process in 2016, taking a hard look at the long term, and what the ATP stands for," he tells me.
  "Can we offer a better service to players and tournaments? Can we do better in our marketing and promotion, and use social media and digital better?
  "We will look at how we connect with our audiences, at our TV coverage, our structure of tournaments. Also how many should be in the calendar, and where they should be based? It will be a major work."
  He says there are "five tennis stakeholders" to consider - players, tournaments, fans, sponsors and the media.
  The ATP's review comes after another successful sell-out World Tour Finals at London's O2 Arena, where close to 263,000 fans watched the top eight players compete.  It brought the overall attendance on the 2015 ATP World Tour season to an all-time record of 4.5 million fans (excluding Grand Slams).
  Mr Kermode says some 15% to 20% of the ATP's annual revenue's annual revenues come from the end of year finals, so as an event it is "financially very important".
  Now, the finals will stay in London until 2018, beyond the original 2016 deadline.
  And Mr Kermode says that while other cities offered more money, they did not provide the profile - or "statement for tennis" - he says they currently enjoy at the O2.
  The 50-year-old also says he has made a conscious effort to present the ATP finals in a different way to other London tournaments, Wimbledon and the Aegon at Queen's (where he used to be tournament director).
  "We have made it an entertainment event as much as a sports event," says Mr Kermode.
  World Tour Finals sponsor Barclays will pull out after the end of 2016, as it cuts back its sport sponsorship, but Mr Kermode says the ATP is confident of finding another big backer.
  "The issue for us at present is whether we go for a two year sponsor deal around London, or a longer deal that is linked to London and another venue somewhere else," says the keen Neil Young music fan.
  "We are talking to five companies as potential sponsors, and want to be quick in securing a deal."
  The ATP has been boosted by the fact that in the past six months it has secured deals worth $160m (Â£106m) over the next five years.
  These include a deal with Emirates, reportedly worth $50m, to replace beer brand Corona as an ATP World Tour sponsor.  The airline's logo will replace those of the Mexican beverage on nets at events.
  New deals have also been signed with Peugeot, Maui Jim Sunglasses, Indian IT services group Infosys, and Chinese online video business Letv.
  Infosys has been given the task of crunching numbers and stats for tennis fans, and sports media, in the same way that IBM does at Wimbledon and SAP does for the WTA women's tour.
  "In the US sports stats are of huge interest, historically less so in Europe," says Mr Kermode. "But many new-generation fans are interested in player statistics, and it is an area we want to focus on.
  "The more knowledge we acquire about our sport, the more fans want it."
  With the sponsorship tank nearly full, he says that there is still room to sign other player-focussed deals with firms providing things like medical services and applications, and fitness products.
  Mr Kermode, who is approaching the last 12 months of his current three year term, says he is keen to stay on for another period in office, but that the final decision lies with the ATP board, not him.
  One projected development he still wants to get off the ground is an end-of-year finals event for the top eight under-21 players in the world.  Originally envisaged for the 2016 calendar, he now says that deadline may be looking tight.
  "A final decision has still to be made," he says, but - whenever launched - it is envisaged the event will slot in between the Paris Masters in late October and ATP finals in London in mid-November.
  As well as giving young players experience of high-level, pressurised, competition in the global spotlight, and thus increasing their ability to compete at the top ends of ATP events and Grand Slams, he also plans to use the event to innovate.
  One of these proposed changes might be to the player warm-up, he says.
  "We currently bring the players dramatically on court at the O2, as though they are coming out for a boxing match, which everyone finds very exciting, " he says.
  "But then you get the player warm up, and things cool off for about 10 minutes. It does not matter if you are in the stadium, there is still that buzz, but it can be bit of a dampener for TV viewers."
  Meanwhile, he remains sanguine about the day when the "Big Four" male players start retiring.
  "Genuinely, I am not worried about it all," says Mr Kermode.
  "It is like when you had the Borg and McEnroe era, then they retired and you had players like Becker, Agassi, and Edberg, coming through."
  He points to players such as Nishikori ("huge in Asia") , Roanic ("that North American presence"),  and Dimitrov ("still to fulfil his potential"),  as well as youngsters such as Kyrgios and Coric.
  "There is a great contrast in styles, and good geographical spread," he says.  "Sport is a very simple business model, basically it is about caring about someone winning against someone else, and that will continue."
target: Men's professional tennis has enjoyed another high-powered year, with record attendances at the Association of Tennis Professionals' (ATP) World Finals in London last month, as well as a number of major new sponsor deals signed.