It's become an increasingly precious jewel in the ATP's financial crown, attracting big crowds and treating the leading players like rock stars since its move to London four years ago.
This week's World Tour Finals not only showcases the top 16 singles and doubles competitors, it also highlights the benefits the men's tennis showpiece can bring to a city.
The question now is, can the UK capital continue its love affair with the tournament -- or will it continue its nomadic past?
Before London was granted an extension to stage it until 2015, New York and Rio de Janeiro were other cities rumored to be in the running.
The Big Apple, like London, is one of the globe's major metropolises and home to one of tennis' four grand slams. It hosted the ATP tournament in the late '70s and '80s in the heyday of Madison Square Gardens.
Brazil, meanwhile, is an emerging market that in the next three years will host soccer's World Cup, the Summer Olympics and a medium-sized tennis event in Rio.
However, moving the event elsewhere would be a "gamble," according to the former head of the ATP's commercial division, while Roger Federer -- whose record six finals wins are spread across London, Houston and Shanghai -- would have no issue with a further continuation.
Tournament director Andre Silva says staying in Britain past 2015 is "definitely" a possibility.
Unlike soccer's ruling body FIFA, which aims to take the World Cup to pastures new, the ATP's goal isn't to be "evangelistic" about tennis -- and London, with its packed crowds, has been a boon financially for the men's game.
"My personality isn't much for a change," Silva, a Brazilian, told CNN. "This is a different animal to the World Cup in that it's year to year, and you do want to expose fans around the world to this type of tennis.
"But the tournament is a very important part of the business of the ATP. More important than exposing everyone around the world to it is making sure it's healthy and not an experiment.
"I know a lot of people talked about Rio and New York. It's obviously great to be wanted. At the same time you need to be sure it makes sense -- and right now London makes a lot of sense."
Federer, who lost to Novak Djokovic in last year's final, shared Silva's view.
"I must agree with Andre in many ways because I think it's important that this event is played in a place that knows tennis," Federer told CNN.
"I think it's good sometimes to play Shanghai, or maybe Lisbon or Sydney for a year, but I think it's not long enough in one place to put its roots down."
Lisbon welcomed the world's top players in 2000 and Sydney did the same in 2001 in another one-year stint.
"It's like a circus," said Federer, who will this week tie Ivan Lendl's record of 12 successive appearances at the season-ending event.
"You come, the tent is there but it's temporary and you move it away again. So here the roots are down, it's successful and that's why if the business makes sense, if the numbers make sense, if the excitement of everybody involved makes sense, I think we should keep it here.
"Other options would have to be considered but it would have to be a great other option."
Richard Davies, the CEO of ATP Properties before leaving his post at the end of 2010, said London was "twice as successful" in monetary value for the ruling body than other host cities.
Unlike when the season finale was showcased in Shanghai as the Masters Cup, the World Tour Finals are operated as a joint venture between the ATP and London's O2 venue owner AEG. All operating costs and revenues feed into the joint venture.
The Shanghai promoters paid the ATP for the right to run the tournament, and the purchasing fee -- believed to work out to about $10 million per year -- was all the latter received from the event.
"If there's no tennis fatigue at the O2 and it's still selling out, I think you have to ask yourself, 'What's the upside to move it elsewhere?' " said Davies. "At the ATP Tour, it's not their responsibility to be evangelistic about tennis.
"London is a great city and that helps corporately. You'd have to take a long, hard look to say, 'We're going to move it.' It's very profitable and to get a tennis-loving nation behind it in any other country at that time of the year will be a gamble."
The success of the tournament has had a knock-on effect on sponsorship, according to both Davies and Silva.