Britain's Cameron Norrie became the final British singles player to fall at the US Open as 24-time Grand Slam champion Novak Djokovic battled through injury to reach the fourth round.

Norrie, 30, has now lost all seven of his meetings with the 38-year-old Serb following a 6-4 6-7 (3-7) 6-2 6-3 defeat in New York.

Djokovic, who is bidding for a standalone record 25th major title, struggled with a lower back injury in the opening set and needed a medical time-out off the court.

The four-time US Open champion asked for more treatment early in the second set.

It is his first tournament since losing in the Wimbledon semi-finals in July - almost eight weeks ago.

"Coming into the match, you want to win in straight sets without any drama - but that's not possible," a smiling Djokovic said in his on-court interview after the match.

"My team wants me to suffer on the court so I can spend more minutes there. Looking from that perspective it is good."