No matter how it ends, both men will always have their spot in one of the most memorable matches in the storied history of the All England Club.
Slugging back and forth over 4 hours, 43 minutes of backbreaking tennis Friday, top-seeded Djokovic emerged with a 7-5, 4-6, 7-6 (2), 6-7 (6), 6-3 victory over del Potro to move one victory away from his seventh major title.
''One of the best matches I've been a part of,'' Djokovic said. ''One of the most exciting definitely. It was so close. You couldn't separate us. Exciting.''
It was the longest semifinal in Wimbledon history and was only five minutes short of the 2008 five-set final between Roger Federer and Rafael Nadal that's also considered one of the greatest matches played on Centre Court.
Djokovic moved into his 11th Grand Slam final, where he'll play the winner of the late semifinal between No. 24 Jerzy Janowicz and No. 2 Andy Murray.
And, yes, that one did begin late — around 6:15 p.m., London time, after Djokovic and del Potro spent the entire, sundrenched afternoon exchanging huge groundstrokes, long rallies and even a few laughs during their marathon, which covered five sets, 55 games, two tiebreakers and 368 points.
''I think this match is going to be memory for a few years,'' del Potro said. ''We play for four hours and a half on a very high level. We didn't make too many errors. I don't know if the rest of the players can play like us today.'' ''Eighth-seeded Del Potro, back in a Grand Slam semifinal for the first time since winning the 2009 U.S. Open, saved two match points in the fourth-set tiebreaker, then won the final four points to take it 8-6.
Shortly after, the match hit the 4-hour mark, guaranteeing it would surpass the 1989 match between Boris Becker and Ivan Lendl — a 4-hour, 1-minute affair — as the longest semifinal in Wimbledon's long history.
''It was a very high level of tennis today, I expected it,'' said Djokovic, whose 80 winners included 22 aces. ''I was ready to play five sets and I stayed tough until the end.''
Del Potro came into the match with his left knee heavily taped, a victim of two nasty slips that sent him tumbling earlier in the tournament. The second fall came two days earlier, on the fifth point of his quarterfinal against David Ferrer. Del Potro said the trainer gave him a couple of ''magic pills'' — anti-inflammatories — and that kept him going in his straight-sets win over the No. 4 seed.
On Friday against Djokovic, del Potro showed few signs of an aftereffect.
Tested throughout by a variety of Djokovic drop shots, del Potro got to most. More than once, the Argentine did his impression of a lanky golden retriever - chasing the tennis ball from wide of the court on the forehand side to wide of the court on the backhand side. After going wide in the third set to hit one of his 48 winners, del Potro stood on the ledge separating the court from the stands, waiting for a high-5 from one of the fans at courtside.
The fans soaked in the del Potro experience, cheering on the underdog as he pushed the world's best player to the very limit.
''They help me a lot for fight, to keep trying, keep going,'' del Potro said. ''Of course I'm sad now, but in a couple of days, I will see how big the match was.''
He may also relive some moments he'd like to have back. Del Potro had three break points in the third set and couldn't convert any, screaming in frustration when he framed a backhand wide on the third try. Then, trailing 3-2 in the third-set tiebreaker, del Potro failed to put an overhead away and Djokovic slipped and fell on the dirt behind the baseline while throwing up a weak lob. Backpedaling, del Potro couldn't handle the overhead and dropped it in the net.
He lost the rest of the points to fall behind by a set.
A bit later, Del Potro lost his serve to fall behind 4-3 in the fourth set, but broke right back, finishing the game with a big backhand winner, a guttural grunt and a fist pump.
They held serve until the tiebreaker, and when del Potro won that one, he looked like the del Potro of 2009, the man who broke the Federer-Nadal-Djokovic stranglehold on the majors by overcoming a 2-1 deficit against Federer in the 2009 final at Flushing Meadows to win the title.
''I think I'm in good form,'' del Potro said.
Against almost anyone else, his court coverage, his sledgehammer forehand and his conditioning on a near-windless 75-degree day would have placed him in the final.
Against Djokovic, the best counterpuncher and perhaps the best conditioned player in the game, it wasn't quite enough.
Exhibit A of Djokovic's ability to turn defense into offense came on set point in the third set, when del Potro pounced big-time on Djokovic's serve, pushing it deep to the Serb's backhand side. Djokovic moved over and calmly blocked it back for a down-the-line winner. Del Potro pulled the neck of his shirt over his face and headed dejectedly to the sideline.
''You can see I played my best tennis ever on grass court, but was not enough to beat the No. 1 in the world,'' del Potro said. ''I was so close.''