Tsvetana Pironkova comes from Plovdiv in Bulgaria, a nation that has not a single grass court (although it sure has no shortage of consonants). It doesn't have a single tennis academy. Pironkova's father is a canoeing champion-slash-tennis coach, which is a little like being a shoemaker-slash-dentist.

Pironkova, ranked No. 82, lost in the first round in nine consecutive tournaments during one horrendous stumble in a generally dismal 2009 (she wasn't the only Wimbledon quarterfinalist who'd just as soon forget 2009; Kaia Kanepi crashed and burned in the starting blocks 11 consecutive times). And Pironkova had won exactly one match at Wimbledon before this year. But she never lost faith. As she said after her sensational upset of Venus Williams in the quarterfinals: "Wimbledon has always been, you know, like a religion to me."

Which sort of implies that Venus Williams is something like Athena, Buddha, the earth mother, Joan d'Arc and Oprah all rolled into one. That made no difference to Pironkova, for even the gods get a little tired of hurling all those thunderbolts and imposing their will on recalcitrant mortals. Pironkova capitalized on Venus' alarming inconsistency (the five-time Wimbledon champion won just 38 per cent of the points played from the baseline, and hit the same low number of aces as her opponent—three—while tossing in four more double faults for a total of five). Pironkova played solid tennis on the key points, which is all that was really required to topple Venus from her pedestal today. The biggest mistake she avoided was trying to play too well.

Pironkova's reverence for Wimbledon is no small thing. It's easy for many of us to forget that in more of the world than not, Wimbledon remains the mecca of tennis, often the only outpost of tennis with which people are even vaguely familiar. Whether Pironkova's reverence for this tournament played a role in her career-defining moment was a factor today can be debated, but the daunting nature of her mission—to play well here in London—can be established. She hadn't set foot on a grass court until she traveled to nearby Roehampton to play Wimbledon qualifying. It was so long ago that she doesn't even remember the year (she guessed 2005); she may be just 22, but as she told us today:

"I started [tennis] ever since I was a baby actually, because my father is a tennis coach. Maybe the first time I hit the ball I was around three years old, and later on I started to play more seriously.  My first tournament I think I played when I was seven years old or something like that. That's pretty much it. My father is a coach. So I spent, you know, almost the whole of my life on the tennis court."

Trying to recall that first experience on grass at Roehampton, she said: "Back then, I thought, Wow, it's impossible. How can I play on this surface? But with every match that I play on grass I feel better and better."

All those hours spent entrenched on whatever baseline was handy back in Plovdiv, and her expanding portfolio on grass, paid off for Pironkova today—a day with a double-barreled surprise for the pundits. While Pironkova stood her ground against Venus, Kim Clijsters went to pieces against a young lady who knows a thing or two about melting down herself, Vera Zvonareva. Clijsters' collapse—although "paralysis" would be a better word to describe her general demeanor in the decisive third set—was especially shocking in light of how well she had played yesterday while wrecking her countrywoman, Justine Henin.

But never mind about that. Clijsters and even Zvonareva are known quantities, each in her own way a flawed competitor to this point in her career. Pironkova, though, is relatively unknown, through no fault of ours. She was refreshingly direct and clear-headed in her press conference. She said of her win, "Well, I didn't have a particular strategy against her. I just tried to play my game, which is like move her as much as possible. I tried to put my first serve as much as I could in the court. Yeah, I think I also did a very good defense. Well, I cannot say what surprised me. But I think it was quicker than I thought. Winning 6-2, 6-3, it was the biggest surprise for me. I expected like a longer match."

So did Venus. But give the older of the Williams sisters credit for how she handled this disaster, if not for how she played. She was forthcoming and humble during the post mortems; there was no trace of the familiar opacity despite the magnitude of her hurt.

"It's very disappointing," she said. "I felt like I played some players along the way who played really well. You know, I think she played really well, too, but maybe not as tough as my fourth round or my third round or even my second round. You know, to not be able to bring my best tennis today and to just make that many errors is disappointing in a match where I feel like, you know, I wasn't overpowered. I wasn't hit off the court or anything, where I just kind of let myself exit. So obviously I'm not pleased with this result, but I have to move on.  What else can I do?  Unless I have a time machine, which I don't."

Venus was particularly weak in the take-charge department. Pironkova is the kind of player who's expert at poking at the dog with a stick. She'll leave an opponent with a chance to take a fairly neutral, mid-court ball, daring her to do something with it, and trust in her own ability to retrieve or counter-punch. She lured Venus into going for too much—although the favorite's inability to produce even just enough was just as much a part of her undoing. Venus put it this way: "I just let it spiral and didn't get any balls in. I mean, I had a lot of opportunities and a lot of short balls. I just seemed to hit each one out."

She wasn't being coy; she made 29 unforced errors, to six by Pironkova.

Some losses—or wins, for that matter—are triumphs of technique. Others are propelled by emotions, intelligence, technique or strategy. In which of those departments was Venus most lacking?

"All." After waiting for the sympathetic laughter to subside, she elaborated: "I didn't bring my best tennis today. And sometimes, like I said, you really have to live in the moment. I got too caught up in the mistakes I was making instead of just letting it go and moving on. I expect a lot from myself, especially at this tournament.  When I missed a few shots, I think I just kind of, you know, maybe was a little too hard on myself. Usually I stay, you know, for the most part, pretty positive."

By any standard, this was a most unusual quarterfinal day at Wimbledon; and here I was, expecting to focus on the journey taken by two fairly obscure players—Kaia Kanepi and Petra Kvitova—into the great unknown kingdom called Semis. As it turned out, neither of them embarked on the trip with a decent GPS. Kaia Kanepi blew a 4-0 third set and multiple match points to allow Kvitova to survive 8-6.

Kvitova was so transported by the challenge that she added a new phrase to the grunting lexicon. Upon winning any of a number of notionally "crucial" points in the final set, she turned to her coach in the player's box and uttered a short, sharp squeal - as if she had just seen a mouse, but had no stool to leap upon to escape.

!102519472 All this means that either Zvonareva or Pironkova will play her first Grand Slam final come Saturday. And on Thursday, Kvitova will have to look across the net at Serena Williams, a cat with considerably sharper, larger claws. Still, Kvitova has a huge game; if she can find a heart to match, Serena will have her hands full. But I wouldn't count on it. Kvitova was asked in her press conference if she believes she can win, and she answered with a frank but not very confidence inspiring "No."

In some ways, Venus losing before she has to meet Serena might be liberating for the surviving Williams. After all, Serena need feel no conflict or stress about having to take part in another intra-family war. Nor does she have to peek at the draw to see how Venus is doing, which must always remind her of their unique, emotionally tricky situation. Did Venus think she made Serena's life any easier by losing today?

"Hopefully it makes everybody's life easier in the draw. . . maybe. But, you know, regardless, I hope that she can win."

Serena also chimed in on the subject, later: "No (it isn't a blessing). I obviously always want her to do well and want her to be right there."

No doubt about it, Serena towers over this reduced field of four. It's hard to see her leaving London an also-ran, but stranger things have happened. And that was just today.