Roger Federer has said that he is "unbelievably happy" to have saved two match points during his five-sets win over Gael Monfils at the US Open.
The five-time Flushing Meadows champion looked to be heading out in straight sets in his quarter-final against the Frenchman, but saved two match points before coming from behind to reach the last four.
The Swiss player told BBC Sport: "It's just unbelievable to win matches like this at Slams. I have won other big ones in other places but over best-of-five, saving match points against Gael in an atmosphere that it was out here tonight, it's definitely very special.
"I'm not sure I have ever saved match point before in a Slam. If that hasn't happened, I'm unbelievably happy that it was today.
"I knew I could play better tennis. When I was down two match points, that's when I wasn't feeling too good any more. I thought 'this is it, don't let him have an easy shot, and go down fighting.' But I served well and managed to turn it around."
Federer will face Croatia's Marin Cilic for a place in the final.
