The greatest of all time discussion in tennis is a difficult one to get to the bottom of.
Spanning different eras and multiple generational talents, settling on one name as the best men’s tennis player of all time is all but impossible.
Impossible for most that is - but Boris Becker isn’t any ordinary tennis fan.
The former world No.1 said Swiss legend Roger Federer was his pick for the best ever, telling Eurosport he believed Federer was, statistically, the most accomplished player of not only his generation, but of all time.
“If you ask about the numbers, Roger Federer is the most successful player,” Becker said.
“If you ask about the best of all times, it's difficult because tennis was played in the 70s, 80s and 90s on different surfaces, so you can't always compare with numbers how good a player was.”
Federer’s record speaks for itself - he has 20 Grand Slam wins, has made 31 Grand Slam finals, and has held the number one rank for longer than anyone else in tennis history.
Despite his incredible record though, challengers have abounded throughout Federer’s career - and none have posed a bigger threat to Federer’s legacy than Novak Djokovic.
Former top-ranked US player Tracy Austin said the Serbian superstar would be her pick for best ever, telling the Tennis Channel Djokovic’s combination of durability and sustained success would be enough to eventually vault him over Federer.
“First of all, he’s not had a lot of wear-and-tear so I think he has another four years,” Austin said.
“Another four solid years where he can win on any surface.
“When Rafa is still around, Rafa’s still the GOAT on clay but I think the fact Novak has that head-to-head already against Roger and against Rafa.
“The fact of the matter is this is the young guy who had to breakthrough and every single major that he won, he’s had to play against Roger and Rafa."
“Roger had a kind of staggered start where he got a couple in before the other two got involved in that three-way trifecta.
“I think that’s been toughest on Novak and at the end of the day I think it’s Novak who’s going to have the most.”
American star Tennys Sandgren said Federer has a more aesthetically pleasing style, but there was a brutal effectiveness to Djokovic that made him hard to top.
“There is no doubt that Federer is more beautiful to look at, but Novak is the best ever,” he said.
“We do one thing and he does another. We try to hit a winner, while he places the ball in difficult and irritating areas, where it is impossible to surprise him.
“He suffocates you slowly. What he does is just incredible.”