An out-of-sorts Alexander Zverev has been dumped out of the US Open after losing a fierce third round battle of wills with compatriot Philipp Kohlschreiber.

The Germans were meeting for the fifth time with Zverev having won the past two encounters but there was little the fourth seed could do to stop an inspired Kohlschreiber, who won 6-7 (1-7) 6-4 6-1 6-3 at Louis Armstrong Stadium.

The versatile 34-year-old showed none of the mental fragility that has dogged him in the past, recovering well after being trounced in the first set tiebreaker to set up a last 16 meeting with Japan’s Kei Nishikori, the 21st seed.

Zverev teamed up with Ivan Lendl before the tournament in New York, bringing the eight-times grand slam champion on to his coaching staff in an attempt to take the next step in his career.

Going by the evidence served up on Saturday, Lendl has his work cut out for him.

“It’s a process,” Zverev told reporters. “I took (Lendl) to do well at slams but this is a process.

“You can’t expect to kind of immediately see the results. I think the results will come next year.

“He told me before the tournament started that, hopefully you’ll do very well at the US Open, but we’re more looking towards… being at the latter stages, competing for slams next year.”

Zverev committed 53 unforced errors, including some double faults at critical moments, and converted only three of his 13 break-point opportunities.

He conceded defeat with a forehand error, sending Kohlschreiber into the fourth round for the fifth time in his career.

“It was a very entertaining match,” Kohlschreiber said in his on-court interview.

“You have Sascha with the big serve, big strokes, but I was very happy with the variety in my play.”

Nishikori, the 2014 runner-up at Flushing Meadows, overcame Argentine 13th seed Diego Schwartzman 6-4 6-4 5-7 6-1.

Earlier, Roger Federer’s 51 winners included a jaw-dropping flick around the net post as he swept aside Nick Kyrgios 6-4 6-1 7-5 to reach the fourth round in a 17th consecutive appearance in New York.

There he will face 55th-ranked John Millman after the Australian defeated Mikhail Kukushkin 6-4 4-6 6-1 6-3, to seal his first appearance in a grand slam second week.

Belgian 10th seed David Goffin was too consistent for German Jan-Lennard Struff in a 6-4 6-1 7-6 (7-4) victory and awaits the winner of Australian teenager Alex de Minaur’s meeting with seventh-seeded Marin Cilic.

Meanwhile, Joao Sousa won three tiebreakers in his 7-6 (7-5) 4-6 7-6 (7-4) 7-6 (7-5) victory over 17th-seeded Frenchman Lucas Pouille.

The unseeded Portuguese will play Novak Djokovic or Richard Gasquet in his maiden fourth-round appearance at a major.