Can Roger Federer find a cure for his US Open blues?

Will Federer struggle again? (2:32)

ESPN's Mark Donaldson and Steph Brantz preview Day 5 at the US Open 2019, where Roger Federer, Kei Nishikori and Elina Svitolina are all in action. (2:32)

NEW YORK -- Roger Federer stood astride tennis like a colossus early in the evening of Sept. 13, 2009, the shadows lengthening on Arthur Ashe Stadium and a 20-year-old upstart, Juan Martin del Potro, the final barrier to a record sixth consecutive singles title.

By nightfall, as spectators tried to blink away their surprise, del Potro lay on his back victorious, limbs outstretched like the points of the compass. Federer's five-year reign at the US Open had come to an end. To most, this seemed an interruption. Nobody would have predicted that in the decade since, Federer would be unable to win another US Open.

But here we are, 10 years down the road, and Federer still hasn't found a way to put together the pieces of the puzzle shattered by del Potro. And so far at Flushing Meadows in 2019, he hasn't been entirely convincing.

"This is supposed to be the easy one," Federer said of the struggle to find his game after Wednesday's 3-6, 6-2, 6-3, 6-4 victory over Damir Dzumhur. When asked why he has had so much trouble jump-starting his genius at the last major of the year, he simply replied: "I don't have an answer to [give] you."

Theories about Federer's US Open blues abound, mostly anchored in the themes of age and fatigue. Even then, coming up with a convincing explanation is a largely unsatisfying drill.

"This fourth major of the year is always seen as the toughest in tennis," ESPN analyst Pam Shriver said in an 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."

Few would argue with Shriver's assessment. But Paul Annacone, Federer's coach for two highly productive years (2010-11) and now a Tennis Channel analyst, is skeptical.

"For most people, I would say, 'Yes, the distractions are a threat.' But for Roger? He's always handled distractions better than anyone I've ever seen."

ESPN analyst Brad Gilbert lends credence to the notion of a physical drain at the US Open, contrasting the event with the Australian Open -- where Federer reignited his career in 2017.

"The courts [here] may be similar to those in Australia," Gilbert said. "But that early in the year , Roger is coming off a little break, and he's had a training block. The US Open is eight months later, after a lot of tennis. He's not 28, he's 38."

Many of the elements that made the US Open the most notorious Slam have been tempered. A player can still feel the hot breath of the demanding New York fans on his neck, but the diverse, cosmopolitan crowd is tamer now than in those early years of Federer's ascendancy. The roof on Arthur Ashe Stadium has eliminated the challenge -- at least for Federer -- of having to play five-set matches on successive days because of rain. The grueling "Super Saturday" format, where the men played semis on Saturday with the women's final sandwiched between them, was finally abandoned in 2013 -- thanks partly to the demands of Federer and Rafael Nadal.

The table has long been set for a Federer renaissance at the US Open, but it hasn't happened yet. And time is running out.

Although anomalous losses by Federer to the likes of Tomas Berdych (quarterfinals, 2012), Tommy Robredo (fourth round, 2014) and John Millman (fourth round, 2018) are not to be diminished, the real key to Federer's 10-year drought seems to be critical back-to-back losses to the great disruptor of the Federer/Nadal rivalry -- Novak Djokovic. It still strains credulity that in the two tournaments after his 2009 loss to Del Potro, Federer fell to Djokovic in the semifinals -- despite having two match points in each match. You don't have to believe in wizards to see how that might cast a hex over a player's subsequent efforts.

The most painful of those failures occurred in 2011. Djokovic swept away the first match point with an atomic forehand winner, which he celebrated by parading in front of the crowd, arms flung high. That blast triggered a reaction in Federer that has been as rare as his Grand Slam losses from match point up. Afterward, he took a swipe at the author of the glorious shot.

Asked if the forehand winner was perhaps borne of Djokovic's confidence, Federer snapped: "Confidence? Are you kidding me? I mean, please."

Clearly referring to Djokovic, Federer sniffed: "Some players grow up and play like that -- being down 5-2 in the third, and they all just start slapping shots. I never played that way. I believe hard work's going to pay off, because early on, maybe I didn't always work at my hardest. For me, this is very hard to understand. How can you play a shot like that on match point?"

In Annacone's eyes, the second of those 2011 match points was the truly painful one. He still recalls in vivid, agonizing detail how one of those trademark, inside-out Federer forehands smacked the net cord, only to fall back on his own side.

"You don't like to see that happen to anyone," Annacone said. "So, yeah, there has been some bad luck. After the loss, Roger told me, 'Look, there are a couple of Slams that maybe I shouldn't have won, either.'"

Those matches, it turns out, may ultimately be the key to how the hunt to become the all-time singles title winner turns out. Djokovic, a 16-time Grand Slam champion (two behind Nadal), is the youngest of the Big Three and the top seed here. He's closing in on Federer, but the most prolific champ (Federer has 20 majors) hasn't given up hope in New York. Federer and Djokovic would face off in the semifinals here should they both advance that far.

Federer said last week that he also has been wrestling with his recent difficulties at this tournament. Could it be that, with his easy genius and knack for skating over the surface of adversity and triumph with equal aplomb, Federer just doesn't get those crucial, tournament-shaping breaks in New York?

"Look, I have no explanation for why it didn't go as well as it could," he said. "I think a bit unlucky for sure, also. That was part of it, yeah."

Federer appeared at Flushing Meadows for his first match with a steely glint in his eyes and, with a few days of stubble on his customarily clean-shaven face, the look of a grizzled veteran. The signal was clear enough: Federer meant business. But he was pushed back on his heels early in his match with qualifier Sumit Nagal.

Federer survived that challenge in four sets, but the stubble was gone for his second-round match with Dzumhur. One thing is certain: Federer is trying every trick in the book. But the book is only so long.