Djokovic, this year’s Wimbledon champion, kept Nishikori under relentless pressure, carving out 17 break point opportunities and winning 80 percent of his own first serve points to win in two hours and 23 minutes, Reuters reported.
“It felt really good,” Djokovic said courtside. “Easier said than done – you have to execute the shots against Kei Nishikori, who is one of the quicker movers on the tour.”
“I thought in the important moments I came up with some good second serves, some good first serves. I was returning well,” Djokovic added.
Djokovic sat out last year’s US Open to rest an elbow injury that eventually required surgery, but that pain and frustration felt like a distant memory on Friday.
“There was always part of me that believed I could come back relatively quickly to the level of tennis that I once was playing,” Djokovic told reporters.
“But at the same time, I felt like the six months off served me very well to find new motivation, inspiration, to recharge my batteries.”
Few would have predicted such a remarkable season for Djokovic, who lost in the fourth round of the Australian Open, underwent surgery on his right elbow and fell at the first hurdle in Indian Wells and Miami on his return.
But Djokovic, who looked on from the sidelines while Federer and Nadal padded their Grand Slam totals, now stands one victory away from winning Wimbledon and the US Open in the same year for the third time in his career.
“These are pinnacles of our sport: majors. It’s where you want to play your best,” Djokovic added. “There is something special about them.
“Especially the top players, they always try to set their own form, so to say, around the Grand Slams because that’s where they want to play their best.”
‘Not my day’
A weary and wounded world number one Rafael Nadal retired from his semifinal while trailing Del Potro 7-6(3), 6-2 on Friday, sending the Argentine back to the Flushing Meadows final for the first time since his 2009 triumph.
Grimacing with every sudden move, the 17-time Grand Slam winner called for the trainer during the changeover on serve at 2-1 in the second.
“I think it was two-all in the first, 15-love, something like this in the first set, that I felt (something),” said Nadal. “I said to my box immediately that I felt something on the knee.
“After that, I was just trying to see if in some moment the thing can improve during the match.
“But no, was not the day.
“I waited as much as I can. You could imagine very difficult for me to say goodbye before the match finish but at some point you have to take a decision.”
Nadal’s stamina and famous fitness have been put to the test on the sweltering Flushing Meadows hardcourts as he has logged nearly 16 hours through five matches.
The Spaniard was made to work for his place in the last four, needing a fifth set tiebreak to see off Dominic Thiem in the quarters.
Nadal’s all out, take-no-prisoners attacking style has seen his body absorb more punishment on the court than perhaps any other player, leaving many to wonder just how long the 32-year-old can continue to pound away.
“All my career everybody say that because of my style, I will have a short career,” said Nadal. “I am still here.”
Del Potro, who has also had his career disrupted by injuries, was not happy to get the victory the way he did but the big-hitting Argentine will now get a chance to raise a Grand Slam trophy nine years after his first.
“It’s not the best way to win a match,” said Del Potro, who also beat Nadal at the same stage of the 2009 US Open.