WIMBLEDON, England—No, not this. Not this, too.

That, I’m willing to bet, is what millions of tennis fans were thinking as Sergiy Stakhovsky inched closer to an improbable victory over Roger Federer late Wednesday afternoon. Was there really another upset, another freak occurrence, in store for us on this freakiest of days at Wimbledon? Six former No. 1 players had already fallen, and many more had taken their own, equally painful falls on the All England Club’s strangely slippery grass. After all of that, I guess, why shouldn’t Stakhovsky, the 116th-ranked player in the world, hand Federer his first loss before the quarterfinals at a Grand Slam in nine years?

And while we're at it, why shouldn’t this day end with the most inexplicable shot of all? Federer was serving, down 5-6 in the fourth-set tiebreaker. He had just saved a match point by lunging for a stab backhand return and following it with a bullet forehand pass; the combination had brought the crowd to a full roar for the first time all match. One year ago, on this same court, Federer had hit exactly that return when he was two points from defeat to Julien Benneteau. Federer had gone on to win that evening; why would anyone in Centre Court believe that he wasn’t about to do the same thing to Stakhovsky today? Why would anyone expect his next serve, at 5-6, to be anything other than a thundering ace?

This time, though, Federer didn’t hit an ace. Instead, Stakhovsky returned Federer’s first serve and the two players rallied. Federer, despite his more powerful ground strokes, didn’t press the issue. He had won the vast majority of the baseline points in this match, and he may have thought that the shanky Stakhovsky would hand him an unforced error—there had to be a reason he was ranked No. 116, right? Again, though, what was expected didn’t materialize. The unforced error, a routine backhand that floated pointlessly wide, came from Federer’s racquet instead. The only explanation I can think of for this shot was that it happened on Wednesday, the Day of Carnage. Federer took his place as the seventh former No. 1 to be sent off, and, when it was over, Stakhovsky became the last of his fellow pros to take a tumble on the grass. But he, at least, was feeling no pain.

Stakhovsky reached that unlikely spot on the Centre Court turf by playing old-fashioned, meat and potatoes, serve-and-volley tennis. There was no choice, he said.

“You can’t really keep up with Roger on grass in baseline rallies,” he said. “It’s just impossible. The only tactics I have is press as hard as I can on my serve and come in as much as I can.”

Asked for an explanation for his win, Stakhovsky said, “Magic.” Afterward, the 27-year-old Ukrainian was both articulate and, admittedly, a little spaced out. “I still have no feelings for what I accomplished,” he claimed. “I’m somewhere lost, I’m sorry.”

Lost off the court, Stakhovsky found more than he had ever found before while he was on it. Every serve, he said, every return, every volley was there when he needed it. He came to the net 96 times and won 61 of those points; he hit 72 winners against 17 errors. Even taking into account Wimbledon’s generous scoring system, those are impressive numbers. Especially impressive was Stakhovsky’s down-the-line backhand volley. Time and again, when he needed a point, he caressed that shot into the corner and out of Federer’s reach.

Serve and volley, as we’re reminded every so often, isn’t dead—or, more accurately, it doesn’t have to be dead. What was striking about Stakhovsky’s version today was that there was nothing flashy or fancy or out-of-this-world about it. There were no 130-M.P.H. serves and few jaw-dropping moments of genius. He just played it the way you’re supposed to play it, put himself in position to make the volleys, and made them. Of course, 17 aces, and some really fast hands around the net, didn’t hurt. Stakhovsky was never faster than when he saved a set point with a winning backhand volley at 5-6 in the fourth. Watching Stakhovsky survive the end of that set, it made me think again that one of the great unsung virtues of serve and volley is that it takes the thought, and to an extent the nerves, out of tennis. You serve, you run forward, you react, you go back and do it again.

Not that Stakhovsky didn’t get tight, or realize what he was trying to do out there.

“When you come here,” he said in his unbroken, British-inflected English, “on the cover of the Wimbledon book is Roger Federer. You’re playing the guy and then you’re playing the legend. You’re saying, Am I about to beat him? Is it possible? When I was up a break in the fourth, you think about it: Really, is it happening?”

“He was uncomfortable to play against,” Federer admitted. “It was difficult to get into that rhythm against a player like that. Credit him for closing it out under enormous pressure. He was better in the important moments than I was.”

Stakhovsky said he was lucky that Federer didn’t find his returning rhythm until late in the match; Federer couldn't find a way to break serve until the fourth set. But it’s the last statement by Federer that matters most: He didn’t win the important points. In fact, Stakhovsky won two more sets in the match, but just one more point, 162 to 161. Big moments and missed opportunities were what bothered Federer the most, because he saw it as part of a trend this season.

Asked if he was surprised that he couldn’t find a way to win, Federer said, “I’m very disappointed in that, that I couldn’t find a way, like I didn’t against Jo-Willy at the French. I thought I had my opportunities, had the foot in the door. When I had the chance, I couldn’t do it. It’s very frustrating, very disappointing. I’m going to accept it and move forward from here. I have no choice.”

Reporters asked him about the end of his 36-Slam quarterfinal streak, but Federer brushed past that quickly. He had the present on his mind. “I guess it’s a great number,” he said. “But moving on from here.” As if to preempt any talk of retirement, Federer said twice that he “plans to play for many years to come.”

More than streaks or records or history, Federer appeared concerned about his play on crucial points recently, points that he’s traditionally won. He even looked, by the middle of the press conference, as if he was already thinking about what he needs to do differently to win them again. That’s a similar dilemma to the one Federer faced, and solved, in late 2011. Maybe that’s one of the few advantages of age: You know there will be dips along the way, but you also know you’ve found your way out of them in the past. Federer said he'll employ "the 24-hour rule," a method he has for not allowing himself to worry about a loss until some time has passed. You don't set a decade-long record for consistency without doing whatever you can to keep a level head. There was frustration and disappointment on Federer’s face tonight, but not despair.

What was on Sergiy Stakhovsky’s face? A disbelieving smile that wouldn’t go away. His moment, at last, had come. Stakhovsky is an intelligent, confident, sometimes wrong-headed and impolitic guy—he’s interesting, and frustrating. He has joined the ATP leadership, because, as he said forcefully tonight, “I think I can change things.” Yet he’s best known as a sort of freelance critic, of equal pay, of the ATP, of tournament facilities, of Federer himself.

Maybe it’s appropriate that on Wedneday, when the world was turned upside down, Stakhovsky showed us his best side. Asked about Federer’s legacy, he said, with near-poetic thoughtfulness, “He’s the biggest name we had and still have, thank God. As a person he showed us that you can be a decent man achieving a lot of things and still be a person everybody admires.”

But Stakhovsky wasn’t so fulsome or worshipful that he couldn’t also say, with a smile that showed he may finally have believed what he had just done:

"Someday I can tell my grandkids, I kicked the butt of Roger Federer.”