Defending champion Djokovic pulls out of US Open

Defending champion Novak Djokovic is out of the US Open after quitting through injury against Swiss 23rd seed Stan Wawrinka as defeat loomed in an electrifying fourth-round match.

Djokovic, 32, retired with a shoulder problem seconds after a double fault left him two sets and a break down.

Loud boos greeted the Serb’s decision, with more heard as he walked off court.

“I’m sorry for the crowd, they came to see a full match but it wasn’t to be,” Djokovic said.

Three-time Grand Slam champion Wawrinka had dominated the blockbuster clash in a boisterous atmosphere at the Arthur Ashe Stadium, producing a powerful display reminiscent of his best to lead 6-4 7-5 2-0 when Djokovic decided he could not continue.

Wawrinka, 34, will play Russian fifth seed Daniil Medvedev in the last eight.