American Tommy Paul ended rising star Ben Sheltons surprise run at the Australian Open to reach his first Grand Slam semi-final in Melbourne.
World number 35 Paul won 7-6 (8-6) 6-3 5-7 6-4 against 20-year-old compatriot Shelton on Rod Laver Arena.
Shelton, still taking online college classes, had never left the United States before travelling to Australia.
Paul, 25, will play Serbias nine-time winner Novak Djokovic or Russian fifth seed Andrey Rublev in the last four.
"This is my first time on this court, my first in the quarter-finals of a Slam. It is also Ben Sheltons first time leaving the States so I think hes had a pretty good tournament as well," said Paul.
"Making it to the second weekend of a Slam is everyones dream when they start playing tennis, so I cant believe Im here right now."
Former world number one Djokovic, the clear favourite for the mens title as he chases a record-equalling 22nd Grand Slam, takes on Rublev at 08:30 GMT.
Greek third seed Stefanos Tsitsipas will meet Russian Karen Khachanov in the other semi-final, with both of those matches taking place on Friday.
Paul, the first American mens semi-finalist at the Australian Open since 2009, reached the fourth round of a major for the first time at Wimbledon last year and had not previously moved beyond round three at Melbourne Park.
But he further extended his best ever Slam run against big-serving world number 89 Shelton, who was bidding to become only the fourth man in the Open Era to reach a semi-final within his first two Grand Slam appearances.
It has been a breakthrough tournament for left-hander Shelton, ranked outside of the top 500 a year ago, as he demonstrated his talent across four victories despite arriving in Melbourne with "no expectations".
Shelton, who hit 24 aces, saw his opportunities limited as he fell two sets down against the consistent Paul, but he seized his chances in the third as he battled back impressively from a break down to force a fourth set.
However, Paul would not be denied again. He restored order with an immediate break of serve and went on to confidently serve out the biggest win of his career after Shelton, who left the court to a standing ovation, forced him to do so by saving a match point.