WIMBLEDON, England—The court-assignment gods did U.S. broadcasters and tennis fans a favor today when they scheduled Sloane Stephens and Madison Keys back-to-back on Court 3. Here we had, for our comparing and contrasting pleasure, two of the three promising young U.S. women’s players currently making their way up the rankings (Jamie Hampton is the third). Stephens, at 20, is ranked No. 17 and has reached a Grand Slam semifinal. Keys, at 18, is ranked No. 52, and is the second-youngest player in the Top 100. What, if anything, did we learn about them in their matches today?

First, we were reminded that it helps to insist on having things your way with the officials. Stephens’ match against Petra Cetkovska had been stopped at the beginning of the third set Friday night because, as Sloane said, “I couldn’t see.” That may sound like an exaggeration, but only if you missed Stephens’ performance in the second set. She was bageled in little more than the blink of an eye, and essentially threw in the towel when she double-faulted twice at 0-3. Sloane said that was around the time when she basically went blind. At the start of the third set, she told Cetkovska and the referee, “OK, you won the set, but I can’t see. We’re going to have to stop.” Despite the fact that other courts on the grounds continued for 30 more minutes, play was stopped on Court 3.

Making that happen was one of Stephens’ few winning moves over the last two sets, but it was a crucial one. She was still way off of her game for most of the third set today, and she fell behind early. Fortunately for her, this time Cetkovska was worse. The Czech was broken at love on a half-hearted attempt at a drop volley, and things went downhill from there. Credit Stephens, despite her own many misses, for taking what was given to her and closing out a 7-6 (3), 0-6, 6-4 win with a couple of decent games. She made 29 unforced errors against just 16 winners, but she also won her second straight three-setter and reached the fourth round at her third straight Grand Slam. Sloane is in the half of the draw that was vacated by Victoria Azarenka and Maria Sharapova on Wednesday. If there’s ever a section of a Slam where “survive and advance” should be the slogan, this is it. Stephens might be able to stagger all the way to the final blind.

“It’s always tough coming back, like, the next day to finish the match,” Sloane said afterward, in her customary off-the-cuff fashion. “I don’t know if I felt pressure. I just felt weird. I’m only playing one set, this is like a practice set. Just had to go out and play hard.”

The second thing we learned today is that winning isn’t always the most important thing when it comes to judging a young talent. Unlike Stephens, Keys lost her match, 7-5, 4-6, 6-3, to fourth seed Agnieszka Radwanska. But her performance was the revelation of the tournament so far. We expected Keys, a big-hitting six-footer, to dictate against the finesse-minded Aga, but not to this extent. Over three sets, Keys hit 15 aces, and belted 67 winners to Radwanska’s 23. Keys’ average serve speed was 17 M.P.H. faster than Aga’s.

None of that was a surprise. Keys is a go-big-or-go-home slugger with a top-class topspin forehand; Radwanska is the tennis equivalent of a hockey goalie—a hockey goalie who can also carve the most diabolically deceptive cross-court drop shot of anyone on either tour. Aga hit a few of those today that left Keys, who lost 6-1, 6-1 to her last year in Miami, dumbfounded. But Radwanska had also lost to another hard-hitting American, Jamie Hampton, last week in Eastbourne, and she’ll always be vulnerable to a player who can put the ball by her at will.

What was a surprise was (1) how well Keys played to steal the second set, just when you might have thought it was Radwanska’s turn to do the same thing; and (2) how hard, and well, Keys fought to stay with Aga through most of the third. Keys saved 15 of 18 break points in the match, and she never got discouraged. Even down 2-5 in the third, she fought off four match points and held serve with three straight aces.

The only caveat I would make is that Keys had nothing to lose in this match. She could fight on today with the knowledge that she wasn't supposed to win anyway. There's a different pressure to playing someone you are supposed to beat.

“I did a lot of things well, so I’m pretty happy about it,” Keys said with a shy smile afterward. “I was kind of impressed with my serving today.”

Keys and Stephens are both powerful and athletic players, but they’re polar opposites in the interview room. Where Sloane is glib and deadpan and Southern California, Keys is ingenuous and soft-spoken and midwestern—after Wimbledon, she’s planning to travel to Illinois to visit her family there. Sloane is a social media adept; Keys isn’t on Twitter.

Here’s Sloane answering a question about what she does when she hangs with her fellow young American players (I think):

“We can talk about like what restaurant we’re going to go to when we go home," Stephens said. "Can’t wait to go here, like Ruth’s Chris, someone else you can relate to. Yeah, I get the crab cakes, whatever.”

Here’s Keys talking about the tennis-pro lifestyle:

“It’s nice. I love that I’m not in school all the time," Madison said. "You know, I love it. I love that I get to do what I love as a job. Very happy and fortunate to be able to do it.”

Words roll of Sloane’s tongue unedited, but they can be an effort for the younger Keys. At times, Stephens can sound like a jaded old pro who has already seen through the media game. Keys, as she said today, has her wide-eyed enthusiasm intact. Both attitudes are understandable: Sloane must be either gunshy or cynical after her Serena-media blow-up this spring, while Keys is still just 18 and cutting her teeth at the pro level.

What matters, of course, is what they’ll do on the court in the coming years. Stephens is the more well-rounded player; she’s more consistent from the ground and a better natural mover. Keys has the bigger offensive weapons—with her serve and forehand, most matches will be on her racquet, as this one was today.

Both are impressive from up close. Stephens' skills, her ball-striking, her easy power, the sound her shots make at contact all make me think that very few players should be able to keep up with her in rallies. But as we know, Sloane doesn’t always make the most of those skills, and she can let things get away from her very quickly, as she did against Cetkovska yesterday. She has won this week, but she’s often won ugly.

Now it seems to be Keys’ turn to make strides. She’s a better, more consistent and resilient player than the one I watched lose to Angelique Kerber in straight sets at the Australian Open in January. She doesn’t have the speed and versatility that Stephens does, but she won't need it if she can hit 67 winners per match. I wondered in Melbourne if she was fierce enough to win Grand Slams, because a fierce drive is the one trait that the Top 3 women today, Serena, Sharapova, and Azarenka, share. This afternoon you might not have described Keys as "fierce"—she can't hide her niceness—but her persistence was much in evidence. She lost, but she was a better fighter today than Sloane.

It’s impossible to know how things will turn out for either Sloane Stephens or Madison Keys, but it’s nice just to have the opportunity to compare and contrast these two young American talents at Wimbledon. After many lean years, it feels good to be able to wonder about, rather than dread, the future again.