Novak Djokovic continued to spin his dark magic in Flushing Meadows on Tuesday night, advancing to his 10th consecutive US Open semifinal when Jo-Wilfried Tsonga retired with a knee injury after going down 6-3, 6-2.

It’s the third time this tournament the world No. 1 has advanced without completing a match. His second-round opponent, Jiri Vesely, withdrew with forearm inflammation. In the third round, Mikhail Youzhny retired after just six games due to a hamstring strain. The nine completed sets he’s played are the fewest for any player who’s advanced to the US Open semis in the Open era. As if the player who’s won six of the last nine Grand Slams needed any more help.

Djokovic was the one who came to New York with health concerns – having just pulled out of Cincinnati with a wrist injury – but in an inexplicable reversal, he’s remained standing while everyone around him drops like flies. Even ESPN analyst Darren Cahill got sucked into the Djokovic vortex, tearing a calf muscle while running down a set of stairs to interview him.

“I can only wish all my opponents a speedy recovery,” Djokovic said cheekily after the match.

In fairness to Djokovic, though, he was almost certainly winning this match regardless of his opponent’s physical condition. After a wobbly first few games, he dialed all the way in, started ripping his backhand, whizzing around the court in a blur, and squeezing the life out of Tsonga.

The additional time off appears to have served him well, though it’s still too early to know whether the comparative lack of match play will help or hinder him when it comes time to face a healthy opponent (assuming that ever happens). Gael Monfils awaits in the semis, and he’s been dazzling this tournament, having won all 15 sets he’s played.

Someone say a prayer for his health.