Andy Murray surged into his first ATP Tour semi-final in the Thailand Open with a 4-6 6-4 6-3 win over this year's US Open semi-finalist Robby Ginepri.
The 18-year-old Briton lost the first set to the third seed.
But Murray hit back to seal victory and will now play Paradorn Srichaphan, who had a walkover against injured Australian Lleyton Hewitt.
Murray's world ranking is now likely to soar into the 80s to cap a wonderful breakthrough year.
"Winning against two top 50 players in a row is a pretty big deal for me, and to get to my first semi-final is also great," said Scotland's Murray.
"I said I would have to serve better than I did on Thursday if I wanted to win, and I think I served very well.
"I attacked when I had to and after the first set played pretty much perfect."
The victory continues the rapid rise of the teenager, who made his ATP debut in April this year when he was ranked 397th in the world.
Murray had the perfect start in the opening set when he broke Ginepri in the first game.
But after taking a 3-1 lead, Murray seemed to lose his way as Ginepri battled back to go 5-4 in front.
Murray looked tired as he served to save the set and the pressure got to him as he tamely surrendered.
The second set was a tense affair but Murray's fitness was not in question as he matched the American for the first eight games.
With the set poised at 4-4, Murray raised his game and broke to 15 in the ninth with a superb backhand, and held his serve in the next to take the set.
Murray continued to pile on the pressure in the decider and although Ginepri continued to serve well, he was becoming increasingly frustrated with his inability to see off the stubborn teenager.
The Briton got the vital break after a lengthy fifth game and with Ginepri losing his cool, Murray broke again in the ninth to seal a famous victory.
His opponent will be home favourite Srichaphan after Hewitt pulled out of the tournament with an injury.
Sixth seed Jarkko Nieminen from Finland sealed his place in the final four by beating Yeu-Tzuoo Wang of Taipei 6-4 6-7 (3-7) 6-4.
Nieminen will have the unenviable task of taking on world number one Roger Federer, who beat Gilles Muller 6-4 6-3.