Leylah Fernandez has showed off her shots, her timing, her fearlessness. In the US Open semifinals, she showed off her smarts

For five games, it looked as if Leylah Fernandez’s glass slipper had finally fallen off.

Before her semifinal with Aryna Sabalenka, I wrote that the biggest question coming in was whether the 19-year-old Canadian could maintain the stratospheric level of her first five matches, or whether she would fall back to earth and remind us why she’s ranked 73rd in the world. But Sabalenka looked, early on, as if she was going to render that question moot. The No. 2 seed was barely giving Fernandez a chance to touch the ball, let alone make any errors with it.

In her first three service games, Sabalenka lost one point. On her first break point, she hit a forehand winner. She seemed determined to send a message down to the other end of the court that this was the big time, she was the stronger player, and she was ranked 72 spots higher for a reason.

If that was the message, Fernandez never received it. She went about her business, stayed in her meditative zone on the changeovers, and, when she came out to serve down 0-3, she did something interesting. Instead of sliding her second serve to Sabalenka’s backhand, which is the safe and natural play for lefties, she took a surprising risk. She changed directions, kicked the ball wide, and hit an ace. Then she did the same thing in the ad court. When she held serve with a forehand winner for 1-3, she was on the board. The crowd, which had been waiting in silence for a reason to roar for her, was alive.

Over the course of her first five wins, Fernandez wowed us with her shots, with her short hops, her deep knee bends, her timing, her positivity and energy and poise and smile. In the semifinals, she showed us her smarts. Rather than being cowed or awed by the power of Sabalenka, a player she had never faced before, Fernandez figured out ways to beat her.

She served to her forehand instead of her backhand. She mixed up the pace on her second serve. She shifted her position and took away Sabalenka’s wide serve in the ad court. She used her backhand drop shot, and measured it perfectly. When Sabalenka forced her to run, Fernandez lofted high balls and restarted the point, instead of trying to match her pace.

“It was definitely a very good match from both of us,” Fernandez said. “She started incredibly well in the beginning. I’m just glad I was able to stay patient, fight for every point.”

It wasn’t, in the end, a very good match from Sabalenka, who had everything to lose. She was facing a younger, less-powerful, lower-ranked opponent, and 20,000 of her supporters. Sabalenka was edgy, and rushed her shots. She made 52 errors and committed eight double faults, including two in the final game. In the second set, after smashing her racquet and firing herself up, she played better, and even earned some applause from the New York crowd, which loves bravado above all else.

But in the end she went for, and missed, too many big shots from too far back in the court.

“This is what we call pressure,” said Sabalenka, who was her usual honest self afterward. “That’s why I’m a little bit disappointed about this match, because, as I said, I had a lot of opportunities and I didn’t use it.”

“Well, this is life. If you’re not using your opportunities, someone else will use it. This is what happened today. I will try to improve it. I will keep working and fighting, and I believe that one day it will come.”

Sabalenka may not be as young as Fernandez, but she’s still just 23, she still has a huge game, and this was her best run yet in New York.

She may also want to take a lesson from her teenage opponent. As she has after her other victories at the Open, Fernandez, specifying her audience, said, “Thanks to the New York crowd” for getting her through. Smart kid: She already knows what we like to hear in the Big Apple.