Rafael Nadal has been tipped to surpass Roger Federer’s Grand Slam record.
The Spaniard moved to within one of Federer’s tally (20) when he won the US Open title last month.
The 33-year-old will next get the opportunity to draw level with his Swiss rival at the Australian Open in January.
Before then, Nadal will move above Novak Djokovic to No 1 in the world rankings on Monday.
“If somebody does it [surpasses Federer’s record], then I think it will be Rafa,” Kiefer told Sky Sports.
“At the moment his goal is to become world No 1 at the end of the year and I think he is favourite, especially after the year he has had.”
Nadal and Djokovic shared the major tournaments this season, winning two apiece.
But Kiefer does not think that will affect Federer too much.
“He has won enough Grand Slams so I don’t think he will be too disappointed at not winning one this year,” he added.
“At his age, he knows what he can do. Overall, I think he can be very, very happy.”
Federer won his 103rd ATP title at the Swiss Indoors on Sunday when he beat Australia’s Alex De Minaur in the final.
He is just six short of Jimmy Connors’ record 109 titles.
“It’s an amazing achievement, winning in his hometown where he grew up, and winning his 10th title. He is getting closer to Connors,” Kiefer said.
“In the best-of-three-sets, Federer is still great so I think he can continue winning these tournaments.
“It might be very close but he has a great chance [of catching Connors] because he is looking fit and healthy.
“I wish and I hope he will be able to continue playing at the highest level for the last couple of years of his career.”
