And it's not just the men's game that is on an upward trajectory.
"I have just come from Istanbul (venue for the season-ending WTA Championships) where the semifinal and final saw 16 and a half thousand people crammed inside the stadium."
"The fact is that women's tennis has two iconic figures at the top in Serena Williams and Maria Sharapova -- it's a potent combination."
The success of the respective men's and women's tours is matched and in many ways surpassed by the four grand slams, with ambitious expansion plans in place for Roland Garros, home of the French Open, and Flushing Meadows, which stages the U.S. Open.
Prize money increases
The Australian Open, first on the calendar in January, recently announced record prize money of $30.68 million for 2013, up by $4.13m.
The eight singles players and top eight doubles pairings in London will share out $5.5 million between them, rising to $6.5 million by 2014, but the likes of Djokovic and Federer, who is president of the ATP Player Council, flexed their industrial muscle this year to demand a more equitable share out of the cash at the slams for lower ranked players.
There was fleeting talk of a strike ahead of the Australian Open if demands were not met and the issue remains a cloud on the horizon on an otherwise sunny sky.
"The future is incredible bright for men's tennis," foresees Drewett, a 54-year-old Australian, who was a former top 40 player himself.
The ATP World Tour Finals is the icing on the cake at the end of a long season, with qualification in the singles and doubles the main goal for the game's elite when they begin their 10-month season.
It's essentially the fifth grand slam and both Becker and Harman believe it will benefit from finding a permanent home in London, extended past 2015.
"It's absolutely astonishing what has been achieved, what they have done with the stadium, the players all love it," said Harman.
Former grand slam finalist Greg Rusedski, working for British television at the event, agreed. "I made two appearances in this tournament in Hanover in the 1990s but this has moved on to another level."
"They have sought to find a proper home for this event," said Harman. "And there's not been a proper home since Madison Square Garden in the 1980s."
Becker would like to see a permanent move: "Tennis is a sport which needs consistency and the reason the grand slams are so successful is everyone knows that at a certain time of the year in a certain place the big stars will turn up," he said.
Rusedski can also see no reason to move while the Paris Masters occupies its present place in the calendar. "Players will not want to travel to Rio de Janiero, which has been touted as venue, at the end of a long season," he said.
It's a potent mix of setting and razzmatazz which defines the O2 experience for the crowd, with players emerging like gladiators to loud music and special effects.
Once the action is underway the crowd is kept in darkness, similar to watching a football match under floodlights, but they are kept in touch with match statistics and disputed line call replays on a giant four-sided screen above the court.