Now Novak Djokovic knows how Andrew Luck felt.

Djokovic, the No. 1 men’s tennis player in the world, was booed Sunday night when a left shoulder injury forced him to retire from his fourth-round match in the U.S. Open. His decision to bow out allowed Stan Wawrinka to advance to the quarterfinals.

Despite his success on the court, Djokovic has yet to receive the level of adulation given to rivals Roger Federer and Rafael Nadal, and judging by the reaction of the spectators in New York, this won’t help his cause with fans.

The defending champion’s trainer repeatedly needed to massage Djokovic’s shoulder to get him through his second-round match last week, and although he said the pain had subsided by Friday’s third-round match, he clearly never got back to 100 percent.

Thumbnail photo via Danielle Parhizkaran/USA TODAY Sports Images