For Federer, it's yet another feather in his Swiss cap. On Sunday, he will play either Novak Djokovic or Andy Murray for the gold.
For Del Potro, this means that he will move on to the bronze-medal match in singles, where a win is necessary to get a medal. The Argentine still has a chance at mixed-doubles gold, though.
But those are just the immediate effects on this particular tournament. The match's real effect is to catapult Del Potro into the position of being a strong dark-horse contender heading into the U.S. Open.
You see, the Argentine won the U.S. Open in 2009, triumphing in an epic final with Federer. After that victory, many believed Del Potro, then just 20 years old, to be the newest threat to the top players in the game.
However, that all changed in 2010. After rising to No. 4 in the world rankings, Del Potro suffered a wrist injury that forced him to miss a few tournaments. With the injury not fully healed, he played the Australian Open and was knocked out of the Round of 16.
From there, Juan Martin ended up missing massive playing time and many tournaments. Eventually, he needed surgery on the wrist to repair it.
Even when he returned to the majors in 2011, Del Potro didn't look the same.
Just this year, though, Del Potro finally showed signs of returning to the top of his game.
Quarterfinal finishes at the Australian and French Opens and a fourth-round appearance at Wimbledon pushed his ranking up to No. 8 in the world, his highest ranking since August of 2010.
So why does today's loss show Del Potro's back with a chance at the U.S. Open?
Well, there are a few reasons.
On a superficial level, the Argentine has never been great on grass courts. Amongst the Grand Slams, Wimbledon has given Juan Martin the most trouble, as he has never gotten past the fourth round.
It doesn't necessarily mean everything, but a good run on a grass court is a good sign for Del Potro.
The real reason, though, is how Del Potro held up physically and mentally in that match.
You see, Juan Martin's heavy shots never let up through the match, a real concern over the past few years due to his wrist problems. Instead, he was able to effectively use those shots to hold serve time and again and almost clinch the win.
Further, Del Potro's ability to continually come back from deficits on his service games showed a level of mental strength we haven't seen from the 23-year-old since his U.S. Open title. That mental strength really helped him in the third set when he broke Federer back at love to force the match on.
So if all these good things came of this loss, why didn't Del Potro win?
Come on—he was playing Federer on grass.
Just don't be surprised to see a nice run from Delpo at Flushing.