Juan Martin del Potro believes that Novak Djokovic can finish his career as the most successful Grand Slam title winner, surpassing Roger Federer's current record of 20. Djokovic secured his third US Open title on Sunday with a 6-3, 7-6 (7/4), 6-3 win over del Potro, taking it to the level with the Pete Sampras mark of 14 Grand Slams. The 31-year-old Serb is now just three from Rafael Nadal and six from Federer. "Of course he can," Del Potro said when asked if Djokovic can claim the record from Federer, who is almost six years older than him.
"He's already 14. He won two Grand Slams in a year, he's healthy, he has a great team working with him.
"Fortunately he, Rafa, Roger will still fight for the Grand Slams, because it's very nice to see them fight for the story.
"We just do what we can against them, but Novak has everything to make records in this sport."
Del Potro was playing in his first Grand Slam final since he lifted the US Open title in 2009 at the age of 20, defeating Nadal and Federer consecutively.
But instead of that victory that demonstrates a launch pad for a sustained challenge in the Grand Slams, Del Potro fought wrist injuries that required four surgeries.
At the end of 2015, his ranking was at 581, he was deeply depressed and was about to leave after having to sit in at least 10 Grand Slam events.
However, when in form, it is a formidable force.
It has 10 wins over the number one players in the world, the most for any person who has never achieved the best ranking.
This year he defeated Federer in the Indian Wells Masters final, while in 2016 he was a key figure as Argentina won its first Davis Cup.
Playing in the third position of his career in the world, Del Potro insists that he is happy to be playing in the era of Djokovic, Federer and Nadal.
"Of course, it's a great challenge to bring them these kinds of tournaments, but I also think we're proud to be close to these legends," said the 29-year-old.
"Throughout my career I've been learning with Novak, Roger and Rafa, watching them win these events very often, it's amazing.
"I do not feel sad because I could not win Grand Slams for them, I'm just one of the guys who are lucky to be in the same era as them, and it's great."
Del Potro reached the final on Sunday encouraging the defending champion and world number one, Nadal, who was forced to abandon his semifinal with an injury.
But he had a record 4-14 loser against Djokovic, including four in the Slams, two of them in the US Open in 2007 and 2012.
"When you see a friend holding the trophy, it's fine, I'm glad Novak is the champion."