Anderson, who appeared in his first semi-final at the All England Club, won 7-6 (8/6), 6-7 (5/7), 6-7 (9/11), 6-4, 26-24 onCentre Court.
As if surviving a six hour, 36-minute marathon was not enough punishment for his body, Kevin Anderson is now hoping his "sore" and "swollen" feet, and "jelly-like" legs will be able to withstand one final test in Sunday's men's final at Wimbledon.
Isner now holds the record for the two longest matches ever played at Wimbledon - this one second only to the American's epic 11-hour, 5-minute classic against Nicolas Mahut in 2010.
Brian Norton was the last South African man to reach the final in 1921.
Three-time Wimbledon victor Djokovic has been waiting all day to step on to Centre Court for the other semi-final against Rafael Nadal, the match where the majority of fans would have exclusively got tickets for - they might not get to see that match now. That one lasted 11 hours, 5 minutes and took place over the course of three days. "Just playing like that, in those conditions, was really tough on both of us at the end, you know.
I really feel for John", added Anderson, who has now made his second final at a Slam after finishing runner-up to Nadal at last year's US Open. Each man also took a turn shouting toward the crowd after capturing a set, and Isner waved a hand toward the crowd during the third-set tiebreaker to generate more cheering. "I can't say it enough, the rule needs to change". But there were, in fact, several breaks of serve.More news: Twelve Russian intelligence officers charged over United States election hacking
"I really hope we can look at it and address it".
With a spot in the Wimbledon final on the line, the two power players beat each other to a standstill in a match that stretched nearly seven hours.
Nadal and Djokovic, meanwhile, are in the midst of their 52nd meeting, with Djokovic holding the edge 26-25.
Anderson finally broke Isner's serve in the fifth set during the 49th game, with the highlight coming during the second point.
Isner got past Milos Raonic in four sets on Wednesday, in a predictably serve-orientated affair, and I expect more of the same against Anderson, who also serves superbly.
They played until approximately 11 p.m. local time under the roof, when play was suspended. However, I am utterly shocked that the markets are finding it hard to split Nadal and today's opponent, Novak Djokovic, for the second semi-final, which will commence no earlier than 1500 United Kingdom time.
They both served well in the remaining games and the 13th game was inevitable and Isner opened a 4-2 lead, only to lose the next point on serve that took the advantage away from him. But if and when Djokovic does break serve, or win a set, or save a set point, or do something to fire himself up and sow doubt in Nadal's head, all of that could be turned upside-down in a hurry, the same way their rivalry has been turned upside-down in a hurry in the past.