The South African is the first man from his country to reach the U.S. Open semifinal since Johan Kriek in 1980.
Despite being seen as a favorite to reach the final from a bottom half of the draw devoid of the game's stalwarts, Querrey said he was "pretty happy" with his run to the quarterfinals, which was his best result in 11 appearances here, and the first quarterfinal appearance at the U.S. Open by an American man since 2011. Anderson advances to the semis to face No. 12 Pablo Carreño Busta, who defeated Diego Schwartzman in straight sets earlier Tuesday.
The second match point was good enough for Anderson, who dominated the rally until Querrey's forehand sailed long.
"He has such a big serve", Querrey said after the match.
Seven-time Grand Slam champion Venus Williams, this year's Australian Open and Wimbledon runner-up, faces two-time Wimbledon champion Petra Kvitova later for a berth in Thursday's women's semi-finals. "You know, I have put in a lot of work".
It was the South African who drew first blood, winning the final five points of the first-set tie-break after Querrey had seemed poised to take it.
Querrey saved a first match point with an ace at 6-5, set up a set point at 7-6, which Anderson staved off by forcing his opponent to slice a backhand into the net.
"Losing the second set was really tough but I played each point at a time and it paid big dividends for me today".
Anderson completed his win over Querrey just before 2am at Arthur Ashe Stadium, after a predictably tight encounter in which breaks of serve were at a premium. "Now, it just happened really quick, I guess".
"I felt I did a fantastic job resetting".
"I just try to learn about how he practices, what he does after practise, before practise, after matches, before matches". "I had my opportunities and I did not capitalise on them. Fortunately, I was able to win a couple more points than him tonight".
Carreno Busta recorded 30 winners to go with 30 unforced errors in the one-hour, 59-minute match.