Tomas Berdych sent mighty Roger Federer spinning to his worst US Open defeat since 2003 on Wednesday and admitted he had succeeded by dragging the world number one out of his comfort zone.
Five-time champion Federer, buoyed by a seventh Wimbledon title this summer which gave him a 17th Grand Slam crown, had cruised through the early rounds at Flushing Meadows, but was out-muscled and out-played by the Czech sixth seed.
Berdych's stunning 7-6 (7/1), 6-4, 3-6, 6-3 victory gave him a first spot in the US Open semi-finals and a Saturday showdown with British third seed Andy Murray, who was beaten by Federer in the 2008 championship match.
"I'm able to make him some trouble, you know. That even if he's playing well there's something in my game that he doesn't like and it makes him struggle," said the 26-year-old Berdych.
"I would say I maybe bring him out of his comfort zone that he always like to be in on court. He always likes to have time and he always likes to be the one who is dictating the game."
Berdych famously shocked Federer in the quarter-finals at Wimbledon in 2010 on his way to his only Grand Slam final appearance.
His free-swinging game was also similar to the tactics employed by unheralded compatriot Lukas Rosol in his second round win over Rafael Nadal at the All England Club this summer.
Nadal hasn't played since.
However, Berdych was not happy to be compared to Rosol, who was ranked 100 in the world when he demolished Nadal.
"I just hope you're not comparing me with Lukas Rosol," he smiled.
"I don't think that we are in the same position. I don't know what else to say. I mean, is it something wrong that we are from Czech Republic and beating big guys? No? Good. OK."
Berdych has always been one of the tour's dangermen, always inside the top 20 since 2006.
But with Federer, Nadal, Novak Djokovic and Murray being so dominant, he often slips under the radar, emerging only when there is a hint of controversy such as at the Australian Open when he was booed for refusing to shake opponent Nicolas Almagro's hand.
For the 1.96m man from Valasske Mezirici in the Czech Republic, who banks his $12 million in the tax-free haven of Monte Carlo, his 10-year career has been all about peaking for moments like these.
"I think I'm a different player than the years before. I would say I'm more experienced than when I beat Roger at Wimbledon," he said.
"This time I made it much better and finished it in the way I did and serving just great. Yeah, it's a bit different. It's another match, another tournament. So, yeah, it comes."
Federer reckons Berdych could go all the way to the title on Sunday.
"If he plays well and serves well and makes the right decisions before and during the match against Murray, obviously he's got a chance. He's beaten him before," said the Swiss of Berdych who leads Murray 4-2 in meetings.
"Then again, it's going to depend on the conditions, day or night. Obviously it's going to be a day session, but you never know with the rain now. So it's an interesting matchup, for sure."