The world's No. 2 ranked player was up 5-4 in the third set and had match point before the eighth-seeded Anderson rallied back to level the sets with a 7-5 victory in the third and winning 6-4 in the fourth set. Disturbed by noises from the crowd, and a plane flying overhead, with the first break of the 5th set, Anderson made no mistake with his service game. The 6-foot-8 Anderson wasn't broken in the final three sets. He had a match point on Anderson's serve in the third set.
And then, slowly, over the next two-plus hours, all the way until the fifth set reached its 24th game, as the temperature dropped and the spectators' cries of "Let's go, Roger!" echoed through the shadows, everything came apart for the eight-time champion.
"Down 2-0 I tried my best to keep fighting and was able to scrape through and by the end I thought I did a great job".
Like Federer and Anderson, Nadal and del Potro Nadal slugged it out for more than four pulsating hours before Spain's 17-times major victor finally landed the knockout punch. And he had held serve 81 games in a row at the grass-court major, a streak that grew to 85 before Anderson broke him a surprising total of four times.
This time a year ago, few would have expected to see either man back in the last-four at the All England Club.
"I wouldn't necessarily say I've been playing like incredible".
Anderson becomes the first South African since Kevin Curran in 1983 to reach the Wimbledon semifinals.
While Trump would have been a distraction in the royal box - especially if the wind were to cut through his hair spray - the 15,000 sunbathers on Centre Court instead have a double bill of Isner and Anderson at 1pm, followed by the main course, Rafael Nadal and Novak Djokovic. "Then you have moments in the match where you rise to the occasion and play very well".
The 32-year-old's prize is a clash on Friday with first-time grand slam semi-finalist John Isner, who ousted 2016 runner-up Milos Raonic 6-7 (5-7) 7-6 (9-7) 6-4 6-3 in a serving shootout featuring 56 aces in four sets. The first set was quickly closed out with a heart-stopping half volley Federer played on the run, without so much as even bothering to bend a knee. I don't think this one naturally you can pinpoint exactly, except my match points. Federer has won all four of the previous head-to-head matchups, most recently taking down Anderson 6-1, 6-1 at the 2015 Cincinnati Masters.
Roger Federer has vowed to return to Wimbledon next year but said he felt "just awful" after a shock five-set defeat to Kevin Anderson on Wednesday. "I still think if had I lost that match point, I made a few steps in the right direction".
"I had my chances so it's disappointing, but he was consistent and solid".
Federer had 33, 14 of which came in the fifth set, while Anderson finished with 31.
"It's feels great to be in the last four of a slam", Djokovic said.
Anderson continued to grow in confidence and stature as the match wore on, holding his nerve to earn his first win over Federer in five attempts.
"I have worked very hard to try and get myself in the best possible shape for the biggest event and this is certainly one of the best".