In one of the most shocking results of the season, No. 19 Tommy Robredo upset No. 7 Roger Federer by a score of 7-6 (7-3), 6-3, 6-4 in the fourth round of the 2013 U.S. Open.
Since the match concluded, the world has been, questioning whether or not Federer will ever win another Grand Slam.
In order for Federer to cure his Grand Slam woes and quiet the critics, however, he doesn't need to make dramatic changes.
Federer hasn't been his normal self, going a full year without a Grand Slam event victory for just the second time since 2002. Semifinals appearances at the Australian Open and a quarterfinals berth at the French Open are encouraging, but he lost in the second round of Wimbledon.
And now he's exited in the fourth round of the U.S. Open.
For the first time in more than a decade, Federer went a full Grand Slam season without a single finals appearance.
Just don't think this signals the end.
Federer's staggering drop-off would be considered a superb season for any player outside of the big four and David Ferrer. This wasn't only the first time Federer went without a finals appearance since 2002, but it was something even more significant.
2013 marked the first time since 2003 that he lost before the quarterfinals in more than one Grand Slam.
There's no question that Federer was off of his game against Robredo, missing some of the shots that we are accustomed to seeing him convert with ease. From forehands that went close to five feet wide to his inability to convert break point opportunities, we saw a side of Federer that we'd never witnessed before.
He converted 2-of-16 break points, committed 43 unforced errors and was just 32-of-52 on net approaches.
Prior to this match, Federer was 10-0 against Robredo and dropped just three sets during that time. Not only does that establish his dominance, but it signals just how much of a statistical anomaly this match was.
Robredo upsetting Federer is one thing, but dominating him in a three-set victory is another conversation altogether.
With all of this being established, Federer doesn't need to go through a complete overhaul in order to cure his woes. The technical prowess is still present and the ability to scientifically pick his opponents apart is a skill that may never disappear.
Effectively, what Federer needs to do is discover his limitations and play within the confines of his declining athleticism.
Arguably, it was once an effortless game for Federer, as he was able to glide across the court with ease and chase down any shot from any direction. His serve was paralyzing and the power behind his ground strokes was enough to overwhelm any player he faced.
For all of the athletic gifts that Federer has long possessed, however, his greatest strength has long been his precision.
That's a skill that Federer still possesses, and the only reason his shots have been off is his inability to mix his level of strength and athleticism with the accuracy of his strokes. With his feet set, his shots are magnificent, but on the move, Federer seems to believe he'll be in a different position to the one he ends up in.
In short, that all comes down to understanding his limits.
Once Federer is able to develop a better feel for what his 32-year-old body can do, he will be able to contend again. He remains one of the most accurate players on the ATP World Tour and can out-duel the best in the world when he manages his strokes.
Expect the great one to bounce back in 2014 if he can develop that understanding.