For all the forehand blasts he retrieved, the ugly falls he suffered and the outright winners he struck in outlasting lion-hearted Juan Martin del Potro on Friday at Wimbledon, Novak Djokovic proved himself a champion of exceptional physical and mental resolve.

But after prevailing in the longest semifinal in Wimbledon history, the top-ranked Djokovic has two more formidable hurdles to clear before he can claim the champion’s trophy: Andy Murray and the British sporting public, which rejoiced when the world No. 2 Scot booked his place in Sunday’s final for a second consecutive year.

On Friday, Murray and his unlikely semifinal opponent, 22-year-oldJerzy Janowicz of Poland, didn’t step on to Centre Court until just past 6 p.m., scheduled to follow the Djokovic-del Potro clash, which lasted 4 hours 43 minutes.

With darkness drawing near, the tournament referee halted the match following the third set so the court’s retractable roof could be deployed — a complex feat of engineering that takes 20 minutes — to ensure play could conclude under the lights without subsequent interruption if necessary.

Murray objected virulently. He was in the midst of a competitive tear, having reeled off five successive games to overcome a 1-4 start to the set. And he shrieked over the development, arguing there was plenty enough light to play on.

“I don’t understand the rules!” Murray railed at the referee. “There are no rules!”

While a younger Murray might have come unglued over the momentum-killer, the mature Murray exited for the locker room, showered, huddled with his coach and returned with new focus, needing just 35 minutes to wrap up the victory, 6-7 (7-2), 6-4, 6-4, 6-3.

From the start of the upset-riddled fortnight, Murray’s advance to the final had been expected by Britons, who have waited since 1936 to cheer a male Wimbledon champion of their own. And Murray proclaimed himself pleased to have done his part to deliver the final British fans longed to see.

But as a competitive spectacle, the match failed to come close to that staged by Djokovic and del Potro, rare sportsmen as well as shot-makers.

“It was one of the most thrilling matches I have ever played,” said Djokovic, 26, Wimbledon’s 2011 champion, of his 7-5, 4-6, 7-6 (7-2), 6-7 (8-6), 6-3 triumph.

And the supremely gifted but often injured del Potro heaped praise on Djokovic for the fight he waged.

“I hit many winners,” said del Potro, the 2009 U.S. Open champion, “and always, the ball comes back.”

With the pride of Serbia and Argentina at stake, Djokovic and del Potro had met on these same grounds 11 months earlier to contest the bronze medal at the 2012 Olympics. Del Potro won that day, declaring himself the world’s happiest man.

On Friday, the 6-foot-6 Argentine took Centre Court with heavy tape on his left knee, which he hyperextended earlier in the tournament. But he vanquished any notion he was unfit for battle.

The Serb claimed the opening set, but del Potro got the service break he needed to level the match at one set apiece.

The third was a deadlocked affair, with the two swapping what seemed like one un-retrievable shot after another. Djokovic gained the critical advantage in the tiebreak when del Potro smashed an overhead in the net at the precise moment the Serb slid on the slick baseline and fell.

By the late stages of the fourth set, del Potro was visibly winded, doubled-over and clutching his shorts after running down so many balls he thought wouldn’t come back. Buoyed by the crowd’s cheers, he played on to force a tiebreak, then fended off two match points. One save required a soul-sapping, 24-stroke rally; the next, a monster serve and forehand into the open court.

Del Potro closed the tiebreak to force a fifth set, then called for a trainer, who kneaded his torso as the player gobbled a banana.

With the match well past the four-hour mark, both players’ touch and timing suffered slightly. They cursed their own mistakes but found occasion to share a laugh, too. Djokovic asked del Potro several times if his knee was fine; del Potro worried each time Djokovic took a bad fall.

And on his third match point, Djokovic sealed the victory with a backhand winner down the line.

“I play my best tennis ever on a grass court, but it was not enough to beat the No. 1 in the world,” del Potro said. “I was so close.”

Note: Americans Bob and Mike Bryan, the world’s top-ranked doubles team, will face 12th seeds Ivan Dodig and Marcelo Melo for Wimbledon’s doubles title Saturday. With a victory, the Bryans would become the first duo to hold all four Grand Slam doubles titles at the same time in the Open Era.

Also Saturday, American Taylor Townsend will take on top-seeded Belinda Bencic for the Wimbledon’s junior girls title. Townsend, 17, of Chicago, advanced with a 2-6, 7-6 (7-4), 7-5 victory over Ana Konjuh of Croatia.