In his quarterfinal match against No. 13 seed Noe Khlif, Jack Sock dropped the opening game for the fourth time on Thursday.

And for the fourth time, he emerged victorious after three hard-fought games, like he did earlier in the day against Rio Newcombe, Max Freeman, and Roscoe Bellamy.

Now, the No. 7 seed is into the men’s singles semifinals after a 4-11, 11-6, 11-6 win over Khlif in their first meeting of the season.

Though Sock is usually known for his serves and forehands—like he was throughout his illustrious tennis career—it was his backhand that lifted him to victory on Thursday.

It also caught the attention of Pickleballtv’s Dave Fleming, who asked about it post-match.

“I don’t have to run around to hit the forehand as much, which is really nice,” Sock mentioned. “I think I’m just gonna label it the ‘Boomstick Backhand’ now because I can actually do something with it, which is a great feeling. I haven’t had that in twenty years of racket sports, so it’s nice to finally have a backhand and be able to do something with it.”

The ‘Boomstick Backhand’—and the rest of Sock’s game—will have to sharp when he takes on No. 11 seed John Lucian Goins next with a trip to Championship Sunday on the line.