Novak Djokovicreturns a shot against Stan Wawrinka. (Photo by Matthew Stockman/Getty Images)
Novak Djokovicreturns a shot against Stan Wawrinka. (Photo by Matthew Stockman/Getty Images)

Federer laughing as Djokovic quits US Open

Defending US Open champion Novak Djokovic is out of this year's tournament after a persistent shoulder injury and familiar foe Stan Wawrinka forced him to retire in the round of 16.

Wawrinka, who defeated Djokovic in the 2016 final at Flushing Meadows, is into the quarterfinals after a 6-4 7-5 2-1 win.

The top-seeded Djokovic blew a 4-1 advantage in the second set and then waved the white flag early in the third.

It promises to make Roger Federer's path to a highly sought after first US Open final against Rafael Nadal much easier after the Swiss star was scheduled to meet World No. 1 Djokovic in the semis.

Federer has his groove back and he proved it by destroying David Goffin to advance to his 13th US Open quarter-final.

After surprisingly dropping the opening set in his first two rounds, the Swiss cruised through his second-straight easy victory by belting David Goffin 6-2 6-2 6-0 in less than 90 minutes.

Federer fired 35 winners and 10 aces to see off the outclassed Belgian on a sunny day at Arthur Ashe Stadium.

The 38-year-old third seed was at his best when it mattered most, converting nine of his 10 break point opportunities to set up a meeting with Grigor Dimitrov, who outclassed Australian Alex de Minaur.

The only drama came early when 15th-seeded Goffin broke Federer to take a 2-1 lead in the first set but the winner of 20 grand slam titles broke back in the next game and cruised to the finish line.

"Sometimes these scores just happen," Federer told reporters. "You catch a good day, the opponent doesn't, then things happen very quickly. I found my groove after a while and was able to roll really. Never looked back."

Roger Federer acknowledges fans after his 6-2, 6-2, 6-0 win over David Goffin. (AP Photo/Sarah Stier)
Roger Federer acknowledges fans after his 6-2, 6-2, 6-0 win over David Goffin. (AP Photo/Sarah Stier)

Goffin was downbeat after his ninth loss in 10 matches to Federer. "I gave completely," Goffin said. "Of course he was great but I gave the whole match. It's tough to say. But, yeah, probably my worst match against him."

The next round should be a tougher test for Federer, against a resurgent Dimitrov.

The Bulgarian was ruthless in his 7-5 6-3 6-4 win over 20-year-old de Minaur. "There's not much to say other than that I'm pleased to be back on a court, pain-free and feeling really good," Dimitrov said in his on-court interview.

Although Federer holds a 7-0 head-to-head record over Dimitrov, the former world No. 3 has taken sets off him on hardcourts.

Meanwhile, fifth seed Daniil Medvedev came from a set down to knock off German qualifier Dominik Koepfer 3-6 6-3 6-2 7-6 (7-2) and reach his maiden grand slam quarter-final.

The Flushing Meadows crowd, angered by what tournament organisers called Medvedev's "visible obscenity" when he gave them the finger two night earlier, were firmly behind Koepfer when he went a set and a break up.

But the Russian kept his cool and eventually prevailed before he again goaded the crowd again with his celebration, although this time the reaction from those at Louis Armstrong Stadium was more mixed. "You give me so much energy to win - thank you!" he said. "You are the best!"

Medvedev, who beat Novak Djokovic on his way to his first ATP Masters 100 title in Cincinnati last month, will instead play Wawrinka.