PARIS—It’s never too late to make a rookie mistake. And Jamie Hampton made a whopper today, even if, technically speaking, there’s no such thing as a rookie in tennis. But this was Hampton’s first Grand Slam fourth-round appearance and—there’s no polite way to put this—she made a mess of it, losing in just over an hour to No. 18 seed Jelena Jankovic, 6-0, 6-2.

I feel alright putting it that way because if there’s one thing I know, it’s that Hampton is much, much better than that.

Of course, Hampton was in a tricky situation. She had just upset No. 7 seed Petra Kvitova in the previous round. She was in the second week of a major for the first time, and she probably envisioned playing on Suzanne Lenglen before a packed house in full sunshine—especially as the previous three matches had raced by, or looked to be doing so until Stanislas Wawrinka found the inspiration to rebound from a two-set deficit to beat Richard Gasquet in overtime, 8-6 in the fifth.

Among other things, that unexpected development ensured that Hampton had to sit around the locker room for a long, long time. And it meant that when Hampton finally walked out there, the light was fading, the air was damp and chilly, and only the hard cases were willing to stick around for more tennis. One of those fans, a leather-lunged Serb actually appeared to have an impact on the match, although there’s still no rule against shouting at the top of your lungs to encourage your idol.

There’s no point in the blow-by-blow. Hampton was out of it almost from the start, flatter than the champagne some of her fans might have uncorked 48 hours ago to celebrate her upset of Kvitova.

Hampton found many ways to lose points. She botched mangled sitters, drove approach shots into the net, and consistently found the doubles alley with her groundstrokes. Meanwhile, Jankovic just took care of business and happily watched her opponent implode. The first set was over in 26 minutes but, believe it or not, it lasted that long only because Hampton mustered the skill and will to fend off three set points before she succumbed to the fourth.

At that point, I probably wasn’t the only one thinking that this might be one of those matches in which the combination of Hampton’s ineptitude—and Jankovic’s focus—was such that there was bound to be a massive swing back the other way. It happens more often than you might think, and Jankovic herself has been known to lose hold of the plot.

For a while, it looked as if that might happen. The American broke Jankovic to start the second set, thanks to a double-fault, followed by a Hampton forehand winner. Hampton then forced a long second game, and even though she was broken, it was just what she needed to slow things down and settle in for a stand.

Unfortunately, the Jankovic partisan fluffing his Serbian flag and exercising his lungs seemed to get to Hampton in the next game. Hampton forced it to deuce twice, and reached a break point. When she hit a lob out and the Jankovic fan let loose once again, Hampton exploded, seeming to direct her anger at him, although later she said that her outburst had nothing to do with the man. “I’ve dealt with that kind of thing before,” she said.

Still, she then made a forehand error to allow Jankovic to advantage, and botched a forehand second-serve return error to give up the game. She would win just one more game the rest of the way.

It may seem unfair to Jankovic to focus this story on Hampton, but her meltdown at this stage of the tournament seemed a much more notable aspect of the match than Jankovic’s steady, crisp, play. Hampton had eliminated Jankovic at Indian Wells the last time they played, and today’s result was a measure not just of how comprehensively Hampton fell apart, but also a tribute to how far Jankovic has come in this current resurgence.

We’ll have time to take a closer look at Jankovic’s fortunes in the coming days.