WIMBLEDON, England—What could possibly top yesterday in terms of amazement, even for the hardened, veteran tennis fan? Monday, July 8, 2013. On that day, Roger Federer will fall to No. 5 or No. 6 in the world rankings (according to my informal Twitter poll and later confirmed by the ITF), a place in the pecking order he hasn’t resided in since June 2003. And, on that day, Rafael Nadal will be ranked no higher than fourth, having managed to lose ranking points at Wimbledon despite only reaching the second round last year. The adjustment in the standings will take some getting used to; it’s as if the All England Club decided to sell apples and cream during The Championships.

With two of the “Big Four” outside the Top 4 in a span of two weeks—Nadal is currently No. 5—the question lingers: Is this era of near unopposed rule-by-quartet in men’s tennis coming to an end?

It will take more than one Grand Slam tournament’s worth of early-round exits—even if Novak Djokovic and Andy Murray follow suit in the coming days—to say that with certainty. Djokovic and Murray are still heavy favorites to collide in the final, and if that happens, can we really say that the four-man force has been removed from power? It would also be the third time in the last four majors they’d meet for the title. Once the clear jayvee to Roger and Rafa’s varsity, Djokovic and Murray may simply be firming up their positions on tour for the foreseeable future.

I’m admittedly getting ahead of myself with that thought, but I’m curious to see what those left in the draw will now accomplish in the absence of Federer and Nadal. Could Tomas Berdych or David Ferrer break through and win a maiden major title? Will Djokovic or Murray wilt under the added pressure to perform? And do we need to think of the many talented fringe players—Richard Gasquet and Bernard Tomic, to name a few—in a different light? These two notable slip-ups have given this edition of Wimbledon an entirely new feel, one I haven’t experienced since I began covering the sport in 2008.

We’ve seen this type of upset before; one occurred here just a year ago. And after watching so many Nadal and Federer escape acts that, over time, defied logic, it wasn’t so shocking to see Steve Darcis give a Grammy-worthy performance as the lead in a Lukas Rosol cover band.

But two such upsets in three days was something I had failed to imagine. Even though, since 2008, Federer had played eight five-set matches before the quarterfinal round of a major. He survived them all, but finally fell off the tightrope Wednesday—in four sets—ending his run of 36 consecutive Grand Slam quarterfinal appearances.

We only know one thing about the future: It will not be like the past. Federer’s streak-snapping defeat let the cat out of the bag, and Nadal’s lethargic loss raises more questions about his long-term future. Still, it would not surprise me to see either of these two win significant trophies over the summer, and in my opinion they are still, for the time being, one half of the game’s Big Four.

But if this tournament turns out to be a turning point in both of their careers, it’s nice to know that the other half of the Big Four is more than capable of leading the sport, having learned from the best for so long.