Djokovic can overhaul Federer's record Grand Slam tally: Del Potro
Juan Martin del Potro believes Novak Djokovic could eventually overtake Roger Federer to become the most successful male player in Grand Slam history.
Djokovic defeated Del Potro at the US Open to win his 14th title, putting him level with Pete Sampras, three behind Rafael Nadal and six adrift of Federer.
But Djokovic is nearly six years younger than Federer and - prior to a two-year barren spell that was ended by his Wimbledon triumph - had been winning Slams at an average of nearly two a season.
Asked if he can catch Federer, Del Potro said: "Of course he can. He has 14 already. He won two Grand Slams in one year. He's healthy. He has a great team working with him.
"Hopefully him, Rafa and Roger are still fighting for Grand Slams, because it is so nice to watch them fighting for history. We just do what we can against them. But Novak has everything to make records in this sport."
Del Potro was back in a Slam final for the first time since defeating Federer to win at Flushing Meadows nine years ago.
Even taking into account all his wrist injury problems, he is certainly one of the players who would have been a multiple Slam winner in another era.
Between them, Federer, Nadal and Djokovic have won 47 of the last 55 Slam titles, but Del Potro has no regrets, saying: "It is a big challenge to take these kind of tournaments from them. But also I think we are proud to be close to these legends.
"During my career I've been learning with Novak, Roger and Rafa, seeing them winning these events very often. It's amazing. I don't feel sad that I couldn't win Grand Slams because of them. I am just one of the guys lucky to be in the same era as them."
For Djokovic, this has been a triumphant summer after his difficulties of the past two years and the low of elbow surgery in February. Returning the following month, he lost back-to-back matches to Taro Daniel and Benoit Paire and his ranking dropped as low as 22.
Now he is back up to third and within striking distance of Nadal in the race to finish the season ranked World No.1.
Djokovic said: "If you had told me in February this year when I got the surgery that I'll win Wimbledon, the US Open and Cincinnati (becoming the first man to win all the Masters titles), it would be hard to believe.
"But, at the same time, there was always part of me that imagined and believed and hoped that I could get back to the desired level of tennis very soon.
"I expected, to be quite frank, after surgery that I'd be back at a high level quite fast. But it took me three, four months. In that process, I learned a lot about myself, learned to be patient, which was never a strong side of me.
"I try to keep both feet on the ground. I love this sport. As long as there is that flair in me, I really will keep on going. I still feel it. I still have a lot of passion. I think more than passion, it's just the will to work and to be dedicated every day."
For Del Potro, the good news is he is playing without problems in his wrist and at a level good enough to put him alongside the three all-time greats in the world's top four.
He cried for a long time after the match and admitted it will be difficult to get over. He said: "I had a good tournament, but this is a tough loss. I'm really sad to lose the final because I had too much passion playing the final, trying to win the title again.
"I think it's time to take a break, to see how my body feels for the future, and then be ready for the next one."