Roger Federer moved to within one win of a record-equalling ninth Wimbledon singles title as he beat long-time rival Rafael Nadal to set up a final against another old foe Novak Djokovic.
Swiss second seed Federer won 7-6 (7-3) 1-6 6-3 6-4 against the Spanish third seed before an enthralled Centre Court.
Federer took his fifth match point for a shot at a 21st Grand Slam, while denying Nadal the chance of a 19th.
Federer, 37, will meet Serbia's top seed Djokovic at 14:00 BST on Sunday.
Federer's eight Wimbledon titles are more than any other man in history and if he beats Djokovic he will match Martina Navratilova's success in women's singles.
"I'm exhausted. It was tough - at the end Rafa played some unbelievable shots to stay in the match," Federer told BBC Sport.
"I had spells where I was serving very well and probably the biggest points in the match went my way.
"That first set was huge, to get the lead and try to protect it. It was a joy to play."
Defending champion Djokovic, 32, goes for his 16th Grand Slam triumph after beating Spain's 23rd seed Roberto Bautista Agut in four sets earlier on Friday.
Djokovic's win ensured it would be a major final between two of the 'Big Three' in the men's game for the first time since the Serb beat Federer in the 2015 showpiece at the All England Club.
'Fedal' produce another memorable Wimbledon evening
Anticipation was high for the meeting between two of the men widely considered among the greatest - if not the greatest - to have played the game, particularly because it was their first Wimbledon showdown since an epic 2008 final.
The names of Federer and Nadal, along with #Fedal40, dominating social media sites signified how the match had captured the attention of fans across the world, while a Royal box featuring stellar names such as Sir David Attenborough, David Beckham and Hugh Grant brought an added sprinkling of stardust.
That 2008 match, played over almost seven hours because of rain delays and ending in virtual darkness in front of a mesmerised Centre Court, is regarded as one of the sport's all-time great matches and it would have taken something extraordinary for the pair to recreate another occasion of such reverence.
Nevertheless, the pair - with a combined age of 70 - did produce a match which will live long in the memory.
Lengthy baseline rallies featuring flawless groundstrokes, supreme athleticism belying their advancing years and scintillating winners - particularly from Federer's backhand - left the 15,000 crowd captivated.
Federer was locked into the match from the moment he delivered an ace with the first ball and, apart from that dip in the second set, neutralised Nadal's weapons in a stellar performance.
After missing four match points, a dramatic ending saw Federer clinch victory in three hours and three minutes when Nadal whacked a backhand long.
Federer's emotion was clear as a manic celebration - at least by his composed standards - greeted the match-winning point, raising both hands to the sky before wildly punching the air.
How Federer sealed victory in a dramatic finale
Federer, who had more support on Centre Court than his great rival in their 40th meeting, edged ahead when he rattled off the final five points in the first-set tie-break but lost his way in the second as his level dipped.
Nadal levelled the match in little over half an hour, but Federer refocused and rediscovered his rhythm to break early in each of the third and fourth sets - and then, eventually, wrap up the match.
Here's how a dramatic finish panned out:
19:29 BST: Federer tees up his first match point on Nadal's serve, returning a first serve with a deep forehand winner. He reaches another first serve down the middle from Nadal but guides it long.
19:30: An ace down the middle means advantage Nadal, but a backhand winner down the line from Federer and a forehand into the net by Nadal brings up a second match point.
19:31: Another first serve landed by Nadal, this time out wide, is batted long by Federer and the Spaniard goes on to hold the service game.
19:38: Now serving for the match, Federer sees off a break point when a forehand into the net after a long rally leaves Nadal crouching on court with his head in his hands.
19:39: Federer comes forward to earn his third match point with a volley at the net, Nadal edging a long rally with a forehand winner to save it.
19:40: With Federer's wife Mirka watching through her fingers, an ace down the middle brings a fourth match point... saved by Nadal with a flicked cross-court backhand winner.
19:42: Federer puts away a clean forehand winner for his fifth match point and seals the match when Nadal goes long after a brief baseline exchange.
'Surprising how aggressive and consistent Federer was' - analysis
Tim Henman, former British number one and two-time Wimbledon semi-finalist:
Historically we've seen Nadal dominate when he extends the rallies. At 37, Federer - you felt - might get tired but it was just phenomenal.
Nadal was always playing catch up. Federer on his serve was always up 15-love you felt, Nadal was never really up love-15 and able to get the crowd on side.
It was surprising how aggressive and how consistent Federer was.
On the back of that performance, it's going to be very interesting to start thinking about the dynamics of the final.
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