New York - Juan Martin del Potro reached the US Open fourth round for the first time since 2012 on Saturday but admitted he cares nothing for the result as he rebuilds his career after being pushed to the brink of retirement.
Del Potro, the 2009 champion in New York, cruised to a 7-6 (7/3), 6-2, 6-3 victory over Spanish 11th seed David Ferrer in the third round on the back of 37 winners.
Del Potro, once at four in the world but now ranked 142 after undergoing a series of wrist injuries, will face Austrian eighth seed Dominic Thiem for a place in the quarter-finals.
He defeated the 23-year-old in their only other meeting, on clay in Madrid this year.
Giant Argentine del Potro has made the last 16 without dropping a set as he continues the red-hot form which took him to the Olympic final in Rio, beating Novak Djokovic and Rafael Nadal on the way.
"It doesn't matter if I win or lose," said the 27-year-old. "I just want to play my tennis again after so many problems.
"If I can hit my forehand again like I did in 2009, then it will be fun for everyone."
Del Potro won his only Grand Slam title in New York in 2009 when he beat Roger Federer in the final, ending the Swiss star's 40-match win streak at the tournament.
But his career was then derailed by four wrist surgeries -- one on his right and three on his left.
Earlier this year, he pondered retirement.
"I am so excited to show my tennis again after my surgeries. I was close to quitting but now I am playing again at a place which feels like home.
"It's an incredible atmosphere, it makes me happy every day."
Ferrer had a 6-3 winning record over del Potro heading into Saturday's third round clash, taking four of the last five.
Del Potro's chequered medical history, however, meant that his win in the Wimbledon quarter-finals in 2013 was the last time the pair met.
The gritty Spaniard looked well set for another victory when he sprinted to a 5-2 lead in the first set before del Potro hit back, much to the delight of a packed Louis Armstrong stadium.
"The crowd was supporting Juan Martin but I am trying to focus on my match, so I don't care," said 34-year-old Ferrer who only finished his second round match against Fabio Fognini at 1am on Friday.
"Juan Martin was better. He served better. He won the first set. He had some doubts in the first set, but in the second and third, he played more aggressive and got more free points with his serve."
Ferrer described del Potro as an "amazing" player after he marked his comeback this year with a silver medal in Rio where he lost a four-hour epic against Andy Murray.
"He was always a very good player. Now he's changing his game because is playing more aggressive with his forehand and with the serve.
"He changed a little bit his game. But anyway, he's amazing player."