If Wimbledon is the truest test in men’s tennis—and based on the last few finals at the All England Club, it’s hard to argue otherwise—then this year’s Championships may reaffirm the stature of the ATP tour’s “Big Four.”

"May" is the operative word, because Roger Federer, Rafael Nadal, Novak Djokovic and Andy Murray haven’t towered above the ranks in the first four rounds. Federer, who’s reached the last seven Wimbledon finals, was nearly ousted on the opening day. Nadal was pushed to five sets twice. Djokovic won just two matches in straight sets. And Murray’s draw, while not as cushy as Duke’s in this year’s NCAA men’s basketball tournament, was pretty kind.

But for all their struggles, the quartet is still singing, while other big names, like fifth-seeded Andy Roddick, aren’t. Last year’s finalist was expected to cruise past Lu Yen-Hsun in the fourth round on Court 2, once known as the “Graveyard of Champions.” It’s not the same court today—and Roddick, of course, has never won Wimbledon—but it felt like an untimely funeral when he lost in five sets despite being broken just once. After his tumble, Roddick painfully admitted, “If I want to consider myself a contender for this tournament, I’ve got to get through that match.”

The Big Four did get through their fourth-round matches, and so did their upcoming opponents. Lu will face Djokovic, Tomas Berdych will take on Federer, Jo-Wilfried Tsonga faces Murray and Robin Soderling has a rematch of the French Open final against Nadal. The challengers are a fearsome foursome. We saw what Lu is capable of Monday, and the others have shown flashes of brilliance throughout the last few years. Berdych has beaten Federer twice, back in 2004 at the Olympics and this year in Miami, when he overcame a match point. Tsonga is a former Grand Slam finalist (2008 Australian Open) and this January he reached the semis in Melbourne. Soderling, seeded sixth and the most dangerous of them all, ended Federer’s streak of 23 straight Grand Slam semifinals at this year’s French Open and is a two-time Roland Garros runner-up.

All four underdogs can pull off an upset—if those facts aren’t enough to convince you, consider the tumultuous Tuesday on the women’s side—but it won’t be easy. Combined, the Big Four is 15-5 against their challengers and each has a winning record against his opponent. Two of those five losses came at Grand Slam tournaments, however: Tsonga beat Murray in the first round of the 2008 Australian Open, and Soderling famously defeated Nadal last year in the fourth round of the French. At Wimbledon, however, it’s (big) advantage Big Four. They’ve all been to the semifinals before; none of their quarterfinal adversaries have.

There’s also the issue of fatigue. While Federer, Nadal and Murray waltzed into the quarters with straight-sets victories, each of their challengers needed at least four sets to advance; Lu and Soderling required five. As for Djokovic, he won in four sets but played 24 fewer games than Lu did in his fourth-rounder. And would anyone dispute that Lu played the match of his life against Roddick? A letdown seems likely.

A performance of that caliber may be what’s necessary to upend a favorite on Wednesday. Going on current form, Berdych and Soderling seem to have the best shots, but would you bet against the two best Wimbledon players of the post-Sampras era? Maybe you fancy Tsonga’s chances against Murray. Just remember, this is only the fifth ATP-level event the Frenchman has played on grass. Plus, aren’t the Brits due for some good fortune? Whatever way you look at it, the quarterfinals present a huge opportunity for the Big Four to assert their authority, and for their challengers to prove they aren’t just flickering forces.

The last time all top four seeds at Wimbledon reached the semifinals was in 1995. Tennis isn’t a team sport—each player is out there only for himself—but it will be interesting to see which foursome turns out to be more formidable.

Ed McGrogan is an assistant editor for TENNIS.com. Follow him on Twitter.