Again, the pair traded breaks early in the fourth, but Anderson broke and eventually served it out to take the match into a decider after three hours and 40 minutes.
Isner and Anderson, both giants capable of enormous serves, just kept blasting the ball past each other, trading service and sides of the court as the rules dictated, but rarely ever competing in a compelling rally.
The 32-year-old is the first South African man to reach the Wimbledon final for 97 years.
Isner and Anderson were no strangers to each other, facing off all the way back to their college days, when Isner defeated Anderson, who played at IL, in the 2007 NCAA Men's Team Final.
The match shattered Wimbledon semifinal records for number of games (the previous record was 72) as well as duration - besting the previous mark by 1 hour, 52 minutes.
Isner and Raonic entered Wednesday night's quarter-final as the two leading players for aces in the tournament at 135 and 117 respectively. Even Anderson himself used the match to call for change in format.More news: John Isner and Kevin Anderson - the everlasting Collegiate bond
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With fellow semi-finalists Rafael Nadal and Novak Djokovic waiting in the wings, Isner and Anderson made the most of their first appearance on Centre Court in these championships - staying on court for six hours. The Swiss was heading into the meeting as a favourite, he had not lost any set in his first four matches of the tournament.
Roanic had only been broken three times this Wimbledon previously but Isner doubled that tally alone to triumph 6-7, 7-6, 6-4, 6-3.
With Friday's match tied 13-13, fans howled after a spectator shouted out, "Come on guys, we want to see Rafa!"
Kevin Anderson is pleading for All England Club officials to introduce deciding tiebreakers after outlasting great mate John Isner in the longest Wimbledon semi-final in history.
Despite going on for almost seven hours, Isner was nowhere close to beating his own record for the longest tennis match history - a first-round victory over Nicolas Mahut, which went on for more than 11 hours over three days and finished 70-68 in the fifth in 2010 also at Wimbledon.
Besides playing for the Wimbledon title, there was plenty of financial incentive for both players. Isner will go home with $743,322.