Andy Murray pulled off the biggest win of his career, beating Roger Federer 7-5 6-4 in the Cincinnati Masters.
Murray's confidence will be sky high after beating Federer
The teenager became only the second player to beat Federer this year, and it was the first time the Swiss had lost before the final for 18 events.
Federer was far from his fluent best, but an inspired Murray took full advantage, breaking serve seven times.
The Scot has struggled to serve out in recent matches, but had no such trouble as he completed his straight sets win.
One of the big strengths of Murray's game is his refusal to bow to anyone on a tennis court, no matter how big his reputation.
I played a pretty perfect match but for a few games at the end of the first set
And he was the aggressor from the start against Federer, who had only been beaten by world number two Rafael Nadal in 2006.
After squandering a glorious opportunity at break point in the opening game, Murray made amends on Federer's next service, pressuring the Swiss to miss with an attempted pass.
It set the pattern for an intriguing match as Federer struggled increasingly with his form under fire from fierce Murray ground strokes down both flanks.
The 19-year-old's backhand was particularly effective and was responsible for securing him a second break after Federer had briefly broken back.
Murray wobbled when serving for the set at 5-4 and his first serve percentage hovered at a lowly 40% all game.
But he immediately created another chance to serve out and duly did so with a booming ace at set point.
Federer (right) was magnanimous - if frustrated - in defeat
Amazingly, the second set followed the pattern of the first, Murray applying pressure on almost every Federer service game and breaking at the first time of asking.
Locked at 4-4, the Briton hit another purple patch, painting the lines to breach Federer's serve for a seventh time.
And he sealed the biggest result of his fledgling career in fitting fashion with a fizzing backhand pass before sinking drained into his chair, towel over face.
"Obviously this was pretty special - I wasn't expecting it to happen today," said Murray afterwards.
"I don't think Roger played his best match, but he has such a reputation that other players think they have to hit the lines.
"I played a pretty perfect match but for a few games at the end of the first set."
Murray played a good match - youngsters play good on the day, but if they play good for the entire week, that's the question
Coach Brad Gilbert agreed with that synopsis: "It was a great win for the kid and, hopefully, that will just boost his confidence even more."
Federer, who has been flawless on the American hardcourts for years, saw a run of 55-straight wins broken.
And he also missed out on equalling Ivan Lendl's record of reaching 18 consecutive finals.
"I would love that the streaks go on and on and on, but once in a while it's also good you lose," said Federer.
"I always draw a positive out of losses, you know, so we'll see what I got to do now the next few days.
"Murray played a good match. Youngsters play good on the day. If they play good for the week, that's the question."