Andy Murray will face Tomas Berdych in the US Open semi-final after the Brit overcame Marin Cilic in four sets at Flushing Meadows.
The Olympic champion was facing a last-eight exit as he trailed by a set and 5-1 in the second, but the Briton staged a remarkable comeback, winning 15 of the last 17 games to reach the semi-final for a third time.
Murray will face Berdych for a place in the final after the world No.7 shocked five-time winner Federer in four sets.
"I've had a lot of tough matches - everyone goes through them," said Murray.
"We've seen Rafa [Nadal], Novak [Djokovic] and Roger struggle here. There is pressure on you to perform well, expectations are high and sometimes you're nervous."
"He played well at the start," he added. "I was a bit tentative, leaving balls and he was able to dictate points.
"I needed to make a move - and I did that. I kept fighting. He got a little bit nervous at end of the second set, which helped.
"It's a very quick court compared to Ashe. I struggled early on and he made it difficult. I'm happy to come through in the end."
For Berdych, who upset Federer on his way to his only grand slam final appearance at Wimbledon in 2010, Saturday's match against third seed Murray represents his biggest match at the US Open.
"It couldn't be better," Berdych said on knocking out Federer.
"There is no better feeling than to play my first night session against Roger and be able to beat him. I really enjoyed it. The crowd were great and I'm really looking forward to the next one."
The other half of the draw sees Janko Tipsarevic take on Spaniard David Ferrer, while defending champion Novak Djokovic plays Juan Martin del Potro, in a repeat of the bronze medal match from the Olympic Games, which saw the Argentine prevail.
Del Potro however, played the role of pantomime villain on Thursday, ending the illustrious career of American Andy Roddick in four sets.
The former US Open champion revealed last week he was set to call time on his career following the end of the final major of 2012, and following defeat to Del Potro, Roddick delivered an emotional speech to the Arthur Ashe Court crowd.
"For the first time in my career I'm not sure what to say," Roddick said.
"I've loved every minute of it. I love you guys with all my heart. Hopefully I'll come back to this place someday and see you all again."
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