“It feels like a crossroads right now,” said Navratilova.
“When Serena doesn’t play it leaves such a gap as she’s been dominating for such a long time. The two biggest names in the game for the last 10 years publicity and personality wise have been Maria and Serena.
“It’s still a big gap between her and the rest of the field but we’re kind of in a generational changing of the guard,” she added.
“It would be nice to have more of a rival to her but that hasn’t been the case for a few years.
“Saying that, the overall game is in great shape because it’s just so international and there’s a nice mix of players from all cultures and countries going at it.
The 57-year-old, who is arguably one of the greatest players to grace a tennis court, popped the question at the Arthur Ashe Stadium. And Russell Fuller tweeted: "Martina Navratilova has just proposed to her girlfriend via the big screen on the Arthur Ashe stadium .. "Martina thanked people for their well wishes by tweeting: "Thanks everyone for your good wishes- I am very happy, so is Julia and our whole family:)".
Martina, who came out as gay in 1981, asked the 42-year-old to marry her on the big screen and her girlfriend said yes much to the crowd's delight. The nine-time Wimbledon women's singles champion popped the question after Kei Nishikori stunned world number one Novak Djokovic in the US Open semi-final.
She said: "I have been waiting for the right time to ask Julia to marry me. The 24-year-old became the first Japanese player to reach a grand slam final after a 6-4 1-6 7-6 (7-4) 6-3 win."I thought this was the right place and the right time to pop the question and thankfully I got a 'yes'."People took to social networking site Twitter to congratulate the former world number one and 18-time women's singles Grand Slam champion. Tammy Vent posted: "Wait, @Martina Navratilova just proposed to longtime girlfriend?!! Former US Open champion Tracy Austin tweeted: "Waiting for our doubles match... Martina Navratilova believes women’s tennis is at a crossroads.Maria Sharapova and Serena Williams have consistently been the game’s most marketable stars but the Russian faces a ban for testing positive for the prohibited substance meldonium while, at 34, Williams is in the twilight of her playing days.And Navratilova raised concerns about filling the void in the pair’s absence.