"They did that again in Paris this year (when Nadal won their semi-final in straight sets)".
A warning for a time violation threw third seed Nadal, who had already squandered four set points, off his service stride in the 10th game and allowed Querrey to break back for 5-5.
"I'm very happy to be in the semi-finals again", Nadal told the BBC after the match.More news: NASA unveils striking space maps charting California earthquakes surface scars
Setting records seemingly every time he steps on court, Federer became the first man in history to register 100 singles wins at a grand slam event with a 4-6 6-1 6-4 6-4 victory over an inspired Kei Nishikori.
The 29-year-old Nishikori entered the quarterfinals having lost to Federer seven times in 10 attempts, despite winning their previous face-off at the ATP Finals in November.
Djokovic is seeking his fifth Wimbledon championship and 17th Grand Slam trophy overall.
Querrey pushed Rafael Nadal hard in the opening set on Wednesday before losing 7-5, 6-2, 6-2 to the third-seeded Spaniard, and said his recent performances on grass has given him a "boost" heading into the American hard-court season.
Battling to hold serve at deuce in the sixth and eighth games, Nishikori managed to keep his advantage and take the first set. But he converted his fourth break point in the next game, then saved three break points at 6-5 before finally clinching the set.More news: UK MPs back same-sex marriage and abortion laws for Northern Ireland
In the blink of an eye, the impostor who had seemingly replaced Federer in the early games was nowhere to be seen as the real deal strode out for the second set and promptly won 12 points in a row to take a 3-0 lead.
In chalking up his 100th win at Wimbledon, Federer became the first player to reach the career century mark at any of the four Grand Slam tournaments.
"It was hard. The beginning was brutal".
The 21st-seeded Goffin started well enough against Djokovic at Centre Court on an afternoon that was humid and sunny but not too hot, with the temperature in the mid-70s (mid-20s C).
Until then, Goffin was playing crisply and cleanly.More news: Piers Morgan to The Duchess of Sussex: 'Go back to America'
The 31 year old no 23 seed revealed he had booked a break in Ibiza with pals this week for his bachelor bash - but that has had to be rapidly cancelled. He hadn't faced so much as one break point against Djokovic, generally considered the top returner in the game. "Most of the rallies went his way". I think he's got one of the best backhands in the game that we have right now.