In a marathon match which was the longest in Wimbledon semifinal history, lasting over five hours on court, Anderson was able to claw back from 2-1 back to seal the victory.
John Isner laid his aces on the table but found a way into the Wimbledon semi-finals by breaking the Milos Raonic serve.
"It's a match that's often won on just a couple points here and there". And the third-set tiebreak was a beauty.
But this time he dug deep to break again in the ninth game on his way to levelling the semi-final at two sets apiece.
The crowd was supportive for hours on end. Isner and Anderson have played each other before professionally and they were rivals in college (Isner, 33, played at the University of Georgia, and Anderson, 32, at University of Illinois).
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. Though Raonic outgunned Isner in that respect - 31 to 25 - he was unable to see through service games as convincingly.
Isner then fell behind 0-30 three separate games on his own serve, including facing one break point, before coming back to hold.
Isner has won eight of the 11 professional matches against Anderson and is projected by many to advance from this battle of two of the game's biggest servers.
"There's hopefully two more matches still to be played".
Anderson took a medical timeout after the third set. But serving for the set, the South African was broken in turn. Each had a chance to close it; Isner ultimately did.
The second semifinal of the day, pitting Rafael Nadal against Novak Djokovic, was easily the most highly-anticipated match of the tournament so far - and its start was delayed well over three hours as the city of London waited for either Isner or Anderson to blink.