If he must, Pete Sampras would nominate Roger Federer as the greatest player the tennis world has ever seen.
But he'd prefer sports fans to sit back and savour the precious remaining years of Federer's grand rivalry with Rafael Nadal, rather than squabbling over who was better.
Sampras returned to Melbourne Park on Friday to do just that himself - but was inevitably asked to join the debate ahead of Federer's semi-final showdown with Nadal.
"Is there one greatest player of all time? I don't know," said Sampras, who boasts one more grand slam singles title than Nadal but possesses three less than Federer.
"I think if you look at the numbers, you have to look at Roger, what he's been able to do: 17 majors, been No.1.
"I believe when you look at the history of the game, each decade has their player.
"Obviously Rod was the best in his time. I certainly had my moments in the '90s. Rafa and Roger are having their moments now.
"You can talk about it for 20 minutes on the different comparisons.
"What Rod (Laver) did back in the '60s - five years he didn't play any majors when he was in his prime, so he could have had over 20 majors.
"I feel like every decade there's the guy. Certainly Roger has been the best player for the last 10 years.
"Rafa is up there with him. (Novak) Djokovic is pushing. So it's really hard to say."
But if pushed, Sampras would lean towards Federer as the GOAT - greatest of all time - because of his consistenty and longevity.
No man can come close to matching the 32-year-old's 23 consecutive grand slam semi-final appearances or 36 straight major quarter-finals.
Federer has also occupied the world No.1 spot for a record total of 302 weeks, 16 more than Sampras - and almost 200 more weeks longer than Nadal's 115 weeks at the top.
"I mean, there's not one greatest player," Sampras said.
"When you look at the numbers, Roger has been so dominant. He's won on all surfaces. He's a phenomenal player."
But so, too, is Nadal, who beat Federer in 22 of their 32 meetings before Friday night.
"Roger's had a tough record against Rafa," Sampras acknowledged.
"He lost some of those matches on clay, which is Rafa's best surface, but there is that argument - Rafa has won all the majors, he's been No.1.
"You could argue that he's well up there.
"If he plays the next four or five years, he could have 17, 18 majors. That's up to him.
"Let's just appreciate what we're watching. It's hard to compare the numbers and the eras where we all did our thing."