Kevin Anderson  vs. Pablo Carreño Busta 
We wondered what kind of craziness might ensue when Novak Djokovic, Andy Murray and Stan Wawrinka all dropped out of the Open. Now we have our answer. OK, Anderson vs. Carreño Busta hardly qualifies as “crazy”—these are two of the game’s straightest faces and least colorful characters—but Grand Slam semifinals don’t come any more surprising. Anderson, after being injured for much of 2016, is ranked 32nd. Carreño Busta is 19th, and neither has been this far at a major before. Both have obviously benefited from a bottom half that included precious few highly-ranked players. While Carreño Busta has played his usual solid game at the Open, Anderson, who is already 2-0 against the Spaniard, has raised his. He has been playing like a man on a mission, and that mission likely doesn’t include losing to PCB for the first time.
Rafael Nadal  vs. Juan Martin del Potro 
“I can be dangerous” against Nadal, Del Potro said on Wednesday night. There’s no question about that. Delpo was fresh off a win over Roger Federer when he said those words, and he has won his last two meetings with Rafa, including a classic at the Rio Olympics last year. Delpo has the assets—height, point-ending power, a two-handed backhand—that typically work against Nadal. Even better, he’s coming off an all-time comeback win over Dominic Thiem, in which he saved two match points. That can leave a player feeling as if everything afterward is gravy, which in turn lets him relax and swing away, a prospect that should frighten any opponent of Delpo’s. But Nadal has improved throughout this tournament, and the fact that there would be no shame in losing this match should also leave him feeling relaxed—or as relaxed as Rafa gets, anyway.