
Serena Williams is currently tied on 22 grand slam wins with Steffi Graf -- a joint-Open era record -- but can move ahead of the German with victory at this year's US Open.

Graf has backed Williams to make the record her own, telling CNN: "It's cool that records are being broken, that's what they're there for. She's been phenomenal for the sport of tennis, it's been great to watch, and I hope she does break it."

While Graf's record could be beaten, she still remains the first and only tennis player to achieve the "Golden Slam" after winning all four grand slam titles and Olympic gold in the same calendar year in 1988.

Graf, who is married to fellow former tennis star Andre Agassi, is also the only tennis player in history to have won each grand slam event at least four times.

Williams, who has yet to achieve the calendar grand slam, won Olympic gold in the singles in 2012 but suffered a third-round defeat to Elina Svitolina at this year's Games in Rio de Janeiro.

"I think she's been unbelievable, she's been amazing to watch," Graf added of Williams. "She's been around for over 20 years and to have a career and play at the level that she's been playing at is pretty unbelievable. I have so much respect for her."

While Graf and Williams hold the joint-Open era record for most grand slam wins, Margaret Court boasts the overall record, with the Australian racking up 24 titles during her career.