Federer and Del Potro meet at Indian Wells with another stunning encounter expected.
The duo have played out some fascinating duels over the years with their 2009 US Open victory still among their most memorable.
Del Potro prevailed on that occasion, sensationally beating Federer to end his five-year unbeaten record at Flushing Meadows.
And, speaking before they met again at Flushing Meadows last year, Federer admitted that the historic defeat still rankled with him – because he thought he deserved to win.
Del Potro was just 20 at the time.
Yet Roger Federer was still angry at the way he failed to beat the Argentinean.
“I felt like that I left that match with a lot of regrets,” Federer explained.
“Probably feels like one of those matches I would like to play over again.
“Feel like I would probably win it somehow because I should have been up maybe two sets to love.”
Today, though, Federer is solely focused on putting Del Potro to the sword.
“Yeah, we have had a lot of close matches. Big matches, close matches,” he said.
“I just tried to think back at the French Open semis, US Open final, Olympic semis, Basel finals … and few [Nitto ATP Finals] matches, Shanghai; just three-setters and five-setters the whole way. It’s been good.
“I think we have an interesting matchup.
“We both know what the other is trying to do, and we try to stop the other person from doing it.
“But it’s hard when me or him is in full flight.
“It’s basically an arm wrestle the whole time, and I think we enjoy that.”