It's never easy to watch, but there comes a point in every tennis legend's career when father time eventually catches up with them.
It happened with Andre Agassi in 2005, Pete Sampras in 2002 and now, for the first time, Roger Federer seems to be approaching that stage of his career.
To be clear, one can't compare the current status of Federer's game to what's happened to fellow Grand Slam champion Andy Roddick's over the last two years.
Federer is still among the best in the world, as evidenced by his victory at Wimbledon early this summer.
But he isn't what he once was, and that's only become clear in the last two months.
First, Federer fell to Andy Murray, the same man he dismantled at the All England Club just weeks before, in straight sets during the gold medal match at the 2012 Olympic Games.
That loss wasn't a huge cause for concern, especially considering how pro-Murray the crowd was, but Federer's recent showing at the U.S. Open was difficult to watch.
Yes, Federer made quick work of Fernando Verdasco in the third round, but even after getting a bye through the fourth round due to Mardy Fish’s withdrawal, he looked like a shell of his former self against Tomas Berdych in the quarterfinal.
Berdych—who has a career-high ranking of No. 6—is no slouch, but Federer is arguably the most dominant individual athlete of the last decade, and after winning the last Grand Slam of the season, no one expected him to fall to a man with no Grand Slam titles to his name.
The resiliency that Federer was once known for wasn’t there. This is the same guy who pulled off the unbelievable comeback against Roddick at Wimbledon in 2009, but after taking the third set in rather decisive fashion, he collapsed.
As the greatest tennis player of all time, Federer still might be able to put together another Grand Slam title, or at least make it to a handful of finals, but he isn’t the dominant force he once was.
There’s no shame in aging, and it’s actually remarkable how long Federer’s been either the best or one of the best in the world, but it won’t last much longer.
As fans, we should savor the next few tournaments Federer plays, because even if he is no longer the best player in the field, we may never see an athlete who trumps his competition to the extent that Federer has for the last decade.