"If he hadn't have won the US Open and played the Laver Cup in Chicago, he probably would have been here," said Ross, who previously worked with US-based sports agency Octagon.

"As somebody who managed and represented pros, I can tell you I wasn't expecting him to come after those results and schedule. Frankly, I'd rather see them not playing than coming but not able to give their best."

Beijing's $3.4 million total prize money－the most in the 500 series－and the growing appreciation of the sport here still attracted a world-class roster this year, including 2009 US Open champion Juan Martin del Potro, rising German star Alexander Zverev and Bulgarian world No 8 Grigor Dimitrov.

And while the absence of the "big four" might be a turn-off for some, Ross believes true tennis fans in China are sophisticated enough to appreciate the quality on offer.

"This is not 2008, this is 2018. Tennis fans here know the players now," said Ross.

"There was a sense in the past that if you don't have Roger, Rafael or Novak or Serena, that the fans don't really get into it. This year is proving that it's no longer the case."

A capacity crowd at the 8,000-seat Lotus Court on Monday during a first-round men's doubles match featuring del Potro and his Argentine compatriot Leonardo Mayer against Zverev and Andrey Rublev of Russia was testament to that theory.

To build on the China Open's 15 years on the WTA and ATP tours, organizers are pulling out all the stops to improve the experience for both players and fans, said Ross.

If Beijing gets the nod to join the Masters series, China will have two such heavyweight tournaments back-to-back in Beijing and Shanghai, where an 1000 event has been staged since 2009.

That will make the already-heavy late-season schedule even more challenging for players.

The ATP Tour now has nine Masters tournaments including back-to-back combos in Indian Wells and Miami in spring, and in the summer Madrid and Rome followed by Montreal and Cincinnati.

Beijing's potential upgrade would create a fourth such tandem in the fall.

"I think the overall calendar can support two Masters events in China just like in the US and in Europe," said Ross.

"It's part of joining the international tennis community and network. This is the way the event is growing and evolving."