Follow The Athletic’s French Open coverageWelcome to the French Open briefing, where The Athletic will explain the stories behind the stories on each day of the tournament.On Day 13, two men’s singles semifinals were slated, but only one was played.How did a semifinal reveal the tennis gap between ceiling and floor?If tennis matches were won by the player who hit the highest level, then Jakub Menšík might have been crowned the victor against Alexander Zverev Friday.Having gone off court for medical treatment early in the third set, when trailing by two sets to love, Menšík, the 20-year-old No. 26 seed from the Czech Republic, suddenly entered a purple patch. He hit two brilliant forehand drop shots, the second a winner, to break Germany’s Zverev for the first time in the match and lead 4-2.A couple of games later, Menšík used serve-and-volley tactics on three straight points to get to 5-3, 40-0. That gave him three set points. He took the first with another sensational drop shot, this time on the backhand side.But what happened in the match before and after was defined by how much higher Zverev’s floor was compared to his opponent’s. When Menšík had dips, especially in the second set, No. 2 seed Zverev, 29, didn’t, instead maintaining a solid level that his opponent couldn’t match over the course of a 7-5, 6-2, 3-6, 6-3 win that sent him into his fourth Grand Slam final.And after Menšík had hit that high to win the third set, it was followed by a dip that felt almost inevitable. Zverev broke his serve to lead 2-0 at the start of the fourth, just as Menšík had finally generated some momentum. Menšík tried another drop shot to start the game, but this time Zverev was onto it, flicking away a backhand passing shot winner in response.Menšík then tried to pull the trigger early with a backhand but sent it into the net, before making a mess of a volley off a powerful Zverev return. Menšík went for too much with another backhand down break point and that was the game, and ultimately the match.“Sascha is third in the world for a reason,” Menšík said in a post-match news conference. “He’s the guy who doesn’t allow you to be longer time in your side of the momentum. So even if I had some great games and had some opportunities, still, with his huge serves and basically, strong game from the baseline, it was super difficult for me to attack him, and of course, as well, to find the momentum and take the momentum on my side.”No sooner had Menšík fought his way back into the contest than it was out of his hands again. Zverev’s level had barely fluctuated in the meantime — he hadn’t played a bad game to be broken, nor had he played an especially good one to break.