Eighth-seeded Anderson's prize for his bittersweet victory over his former United States college friend and rival is a date on Sunday with either world No.1 Rafael Nadal or fellow grand slam giant Novak Djokovic.
The final set alone lasted for two hours and 50 minutes.
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. Because of the length of the first match, that semifinal will be played with the roof closed.
And when asked about his upcoming semi-final, Isner said: "It's a huge match, for sure".
As the fifth set dragged on and on, the American Isner appeared more visibly exhausted and had to survive more scares on his own serve than Anderson.
In the third set, the 33-year-old American fended off two set points and won the tiebreak 11-9.
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Each player held his next serve before Anderson broke Isner again to go up 5-4 and then proceeded to serve out the set to send the match to a decisive fifth set.
Anderson will play again in the final on Sunday - hopefully there, a victor will be decided in four sets or less. It was a drama filled set that went back-and-forth, similar to the third set.
Isner did, however, break the record of the most serves at a tournament - beating Goran Ivanisevic's 213 on his way to the Wimbledon back in 2001.
At 24-24 Anderson took a tumble but managed to get to his feet and hit a left-handed shot inside the baseline, taking the point for 0-30.
Nadal and Djokovic will battle for Sunday's final on the same court at 4pm.
He is chasing an 18th Grand Slam title which would put him just two behind Federer. We played each other in college probably three, four, five times.