This is the beginning of the end of tennis' Big Three as we know it

Dimitrov upsets Federer to advance to semis (2:13)

Grigor Dimitrov gets his first win against Roger Federer in a tough, 5-set match to send him to the US Open semifinals. (2:13)

NEW YORK -- It was the last place Grigor Dimitrov might have imagined seeing himself as little as a week ago: ahead by a service break in the fifth set of a quarterfinal at the US Open on a Tuesday night, in position to close out Roger Federer as stunned fans packed into Arthur Ashe Stadium looked on.

Dimitrov had come into the match at low ebb, having slipped to a ranking of No. 78 (his lowest since June 2012). He had won just one match in his eight previous tournaments. It didn't matter. He had come determined to shatter an icon, one against whom Dimitrov had been winless in seven previous attempts. And it didn't matter. He sensed his time had come and accomplished his goal with a bravura display of shot-making -- sometimes spectacular shot-making -- to win after three-plus hours, 3-6, 6-4, 3-6, 6-4, 6-2.

A decade ago, when Dimitrov was merely a conspicuously talented 18-year-old cutting his teeth on the pro tour, his liquid movement, deft touch and radiant one-handed backhand earned him the nickname "Baby Fed." It took him most of a career to finally live up to the moniker, but he did it on one of the game's greatest stages on a crucial occasion.

Why here, and why now, after so many disappointing results?

"Different circumstances, different court, different time of the tournament," the Bulgarian, now 28, said afterward. "I mean, I can say so many things that are different. I was more present, to be honest. I was more of myself. ... In the past, it's always been very hard to play against him."

Thanks to Dimitrov's fit of brilliance, New Yorkers will continue to be denied the pleasure their counterparts in the Grand Slam cities of Melbourne, Australia, Paris and London have experienced, some on more than one occasion: a Grand Slam clash between the twin icons of tennis, Federer and Rafael Nadal. They have never met at any stage of this tournament.

That probably is the least of Federer's worries. He came into the US Open hoping to wipe away the aftertaste of the painful loss he took against top-ranked Novak Djokovic in the historic first Wimbledon final to be decided by a fifth-set tiebreaker. Instead, he absorbed another five-set defeat. In addition, he also went the distance only to lose in the 2018 Wimbledon quarterfinals against Kevin Anderson.

The beaten all-time Grand Slam singles champion praised Dimitrov's poised, precise baseline play, and the degree of consistency that enabled him to hit 19 fewer unforced errors than Federer (who misfired a cringeworthy 60 times). It was a match of fast and furious rallies, with a fair amount of slapdash ballstriking by both men. "That [baseline play] is something in the past I've always been able to dominate," said Federer, who won only five of 13 rallies that lasted for longer than nine shots. "That was not the case tonight."

When Federer called the trainer at the end of the fourth set and took a medical timeout, leaving the court to receive treatment in an attempt to loosen up his stiff upper back and neck, it didn't help; if anything, the break seemed to hurt him. He refused to blame his loss on the injury.

"I just needed to try to loosen it up, crack it and see if it was going to be better," he said after the match. "But this is Grigor's moment and not my body's moment, so ... it's OK."

The match marked the second successive year Federer was eliminated from the US Open by a player ranked outside the Top 50, and the 11th year Federer has failed to bag another US Open title, after having triumphed in Flushing Meadows for five consecutive years ending in 2008. It's a baffling detail, for which no one really has a convincing explanation.

"This fourth major of the year is always seen as the toughest in tennis," ESPN analyst Pam Shriver said in a recent interview. "The late nights, the heat, the chaos of the entire New York scene. You don't know it's draining you, but it's taking a little bit more from you each day."

Dimitrov said Federer had always come out "fiery" in the past, putting him back on his heels. The big difference Tuesday evening was that losing the first set did nothing to dampen Dimitrov's enthusiasm. "I felt very comfortable from the first point, despite the fact that I was missing a little bit here and there," he said. "I kept on believing in what I had to do, in my game plan."

Part of that game plan was to keep Federer on the court for as long as possible. Dimitrov executed it well, content to draw Federer into a war of attrition. Even when it looked most grim for Dimitrov, when Federer won the third set, Dimitrov clung to the idea he could wear out his rival.

The high point of Dimitrov's winning strategy was the seventh game of the fourth set, with Federer serving at 2-4. The game went on for nearly a half-hour and contained 22 points, including seven break points for Dimitrov. Federer finally held the game, but while it might have fired hopes that Federer would make a final push, Dimitrov sensed Federer's game -- and spirit -- were finally broken.

"I was very happy, even though I lost the game," he said. "I did exactly what I wanted to do. I was actually smiling going through the changeover because I [knew that] game must have hurt him a lot. For me, it actually filled me up."

Federer's form degenerated visibly in the ensuing games. Dimitrov fell behind 0-40 when serving for the set at 5-4. He wiped away those break points and dismissed a fourth. Facing a fifth break point, Federer hit a feeble backhand into the net. He turned away from the court, a bitter, ironic smile on his face. He laughed, then half-heartedly failed to keep Dimitrov from winning the next two points, sending the match into the decisive fifth set.

The end was anticlimactic. Federer returned from his medical timeout and was promptly broken to start the final set. Soon he was merely waving at balls -- swatting them into the net or outside the lines. He looked deflated, and it was difficult to watch.

Federer has faced innumerable tough assignments before, usually coming through with flying colors. But he's 38 years old now, and the familiar question -- "How much longer can he go on?" -- resonates ominously. His genius for the game has kept him competitive at the highest level. He is still ranked No. 3 in the world, with a stellar 43-7 record in 2019. But he has become increasingly vulnerable to players outside an elite circle of peers led by Djokovic and Nadal.

Aging players are more prone to having inexplicable bad days, and Tuesday was one of those for Federer. When he dropped the opening set in each of his first two matches here, it seemed the handwriting was on the wall: No one who has done that has rebounded to win the tournament. But Federer gave reason for his fans to hope. His next two wins were swift and clinical, lasting a grand total of just two hours and 38 minutes, or about the time it took for him to play four sets against Dimitrov.

Federer described the loss as a "missed opportunity," partly because he led at one point by two sets to one and knew, in the back of his mind, the winner would get two days off (thanks to the USTA's unique scheduling) before facing first-time Grand Slam semifinalist Daniil Medvedev. Federer is too professional to have taken Dimitrov for granted, but at some point, he also knew the match was low-hanging fruit, the reward for winning enormous.

The last US Open that didn't have at least one member of the Big Three in the semifinals in 2003, when the quartet comprised Juan Carlos Ferrero, Andy Roddick, Andre Agassi and David Nalbandian. Nadal is the favorite in the last quarterfinal (he faces Diego Schwartzman on Wednesday), as he will be if he reaches the final, no matter who fights through in the top half of the draw.

The atypical early exits of Federer and Djokovic (who retired with a shoulder injury during his fourth-round match against Stan Wawrinka), as well as the physical setbacks experienced by Andy Murray, suggest the Big Four is no longer a viable entity. Nor can the Big Three be relied upon going forward to perform with their customary efficiency.

For years now, fans have wondered when the logjam created by the Big Four will implode, opening up the game to a brisk flow of new talent. It probably is happening right now, but the Big Three are also engaged in a tense race to determine who'll retire with the largest haul of Grand Slam singles titles. Federer still leads with 20, while Nadal has 18 and Djokovic 16. The motivation for each of them to prolong his career as long as possible is powerful.

Federer wasn't much in a mood to talk about what the future holds after Tuesday's loss, as he was again asked whether he thought he'd have another opportunity to win another Slam title.

"If I think I am going to get more opportunities?" he asked.

"To win Grand Slams at [age] 38," a reporter clarified.

Federer quickly replied: "I don't have the crystal ball. Do you?"