Australian Open: 'I didn't deserve this one but I'm standing here,' Federer saves 7 match points to enter semis

Roger Federer admitted that he did not "deserve this one" after he defeated unseeded American Tennys Sandgren in a thrilling quarter-final fixture at the Australian Open on Tuesday.

Federer, who saved an amazing seven match points, conquered form and fitness before he clinched the match -3 2-6 2-6 7-6 (10-8) 6-3 inside four hours in front of a charged-up Rod Laver Arena crowd in Melbourne.

"You've got to get lucky sometimes I tell you that. Sometimes you're not under control. I just hoped he wouldn't smash a winner, just keep the ball in play and if he does miss one of two then see what is going through his mind.

As the match went on I felt better and the pressure went away. I didn't deserve this one but I'm standing here and I'm obviously very happy," the 20-time Grand Slam winner told Jim Courier in the post-match interview.

Federer, who took a medical time out for a groin issue, will face the winner of Novak Djokovic and Milos Raonic's quarter-final match.

Federer, who had not played since the ATP Finals in November, has faced only unseeded players this Australian Open and the matches have all been tough – something the former No. 1 would not have expected. He almost lost his third-round match to Australia's John Millman. But, a fightback from 8-4 in the 10-point match tie-break kept Federer alive in the year's opening Grand Slam.

Even on Tuesday, the Swiss Maestro won the opening set 6-3 before his game began to fall apart as he ended up losing the next two sets 2-6, 2-6. World No. 100 Sandgren, who aimed to be the lowest-ranked player to reach the Melbourne semi-finals since 1991, could not convert even one of the seven match points he had earned.