McEnroe said Williams would be ranked "like No. 700 in the world" in the men's game, with Williams responding to tell McEnroe to "keep me out of your statements that are not factually based."
Now 34-year-old Tursunov has added in on the debate.
"I would hope that I would win against Serena," Tursunov told the BBC. "It would be a similar argument to: who would run faster, the fastest woman or the fastest man? Tennis is becoming more and more a physical sport, so it's going to be hard for a woman to beat the men.
"It's not black and white. There are lots of factors to take into account. Physically I might not be in the best shape of my life, but as an overall package, I'm much better than my ranking would suggest. She is pregnant, and I'm not.
"I've never heard John say anything absolutely stupid. He knows his stuff. What he said about her being an incredible player is correct -- explosive, powerful and she puts in a lot of work. But I would hope that I would win."