Reigning world's no.1 and 18-time Grand Slam champion Serena Williams has already accomplished a lot of things over two decades of excellence that her entry into the tennis Hall of Fame is not anymore a subject for debate. The pressing question now is Serena already the greatest women's singles player of all time?

In a poll conducted by Sports Illustrated, a whopping 68 percent of the voters believed Williams have achieved enough for her to be recognized the best women's tennis has ever seen, while 32 percent of the votes says the other way around.

Aside from the survey, veteran tennis writers Kirk Gimenez of SportsNet New York and Ben Reiter of Sports Illustrated were also present to share their opinion on Williams' place in tennis history.

Gimenez asserted the Williams has been the cream of the crop of the present era, but her body of work is still no match to the standard set by German netter Steffi Graff during her era.

Gimenez stressed that Graff's unprecedented 1988 season run, which saw her winning the Australian, French, Wimbledon and US Open along with a gold medal in women's tennis of the Seoul Olympics cemented her place as the greatest female tennis player of all time.

"I am old enough to remember Stefi Graff and that 1988 season," Gimenez stated. "Single calendar year, golden slam, won the Olympics. She took everybody by storm. Martina was still in the game, Chris Evert was still in the game. And everybody was just amazed who was this 19-year old kid. She was dominant.

Meanwhile, Reiter has different take and he gave his vote to Serena Williams because of the level of athleticism and competition present in women's tennis in the present era.

"I think the level of athleticism across the world, across the globe in women's tennis is in such a higher level than the time of Graff, Evert and Navratilova," Reiter stated. "And Serena is still peaking up and looking for more slams in her 30s."

With 18 Grand Slams, the 33-year old Williams is now four major titles shy of equalizing Graf's 22 Grand Slam crowns the German collected from the late 80s up to the late 90s.

Who do you think is the greatest tennis player of all time? Is It Serena Williams or Steffi Graff?