"We've been able to take the average career length from 12 years to now 15 years. I'd rather have 15 years of a superstar than a couple of great years then injured," Allaster said.

"Both Serena and Venus are a gift to women's tennis. Venus is thinking long term and I know Serena is, along with others."

The WTA's pressing business goal is to find a replacement for main sponsor Sony, which concluded an eight-year partnership at the end of 2012.

"We'll get through that. I'd like to have it for 2013 but usually a sales cycle for a global multimillion-dollar sponsorship is 18-24 months, and we are 10 months into this," Allaster said.

And if there is ever any hint of complacency about continuing the WTA's success, Allaster will remind the players of the words of that pioneering nine.

"They're proud of women's tennis and proud of our success. A couple of them looked at me poignantly and said 'Don't let them catch us.' We didn't work this hard for women's tennis not to be No. 1."