Federer saves seven match points in 'miracle' escape

Melbourne: Swiss great Roger Federer said "I believe in miracles" after he saved seven match points in a five-set nail-biter against 100th-ranked Tennys Sandgren to go into an Australian Open semi-final with Novak Djokovic on Tuesday.

The six-time champion, struggling physically, saved three match points at 4-5 in the fourth set and four more in the tie-breaker to scrape through 6-3, 2-6, 2-6, 7-6 (10/8), 6-3.

Federer, 38, now goes into an unmissable semi-final with Djokovic, who blunted Milos Raonic's razor serve to win 6-4, 6-3, 7-6 (7/1) and move two wins from an eighth Melbourne title.

Djokovic, despite trouble with his contact lenses, ended Raonic's run of 63 straight games in the tournament without a break of serve and moves smoothly into the semis for the loss of just one set so far.

He paid tribute to the great escape by Federer, ahead of a semi-final that reprises his epic win over the Swiss in last year's Wimbledon decider.

"What he did today was really amazing, to come back and save seven match points at his age," Djokovic said.

"He's still playing such a great tennis and proving that he deserves to be up there. He's a great fighter. Obviously I have lots of respect for him."

Federer's match was incident-packed and he received a rare warning for an audible obscenity before going off-court for treatment on a groin injury.

Still hampered by the injury, he somehow forced a fifth set and began to regain control against the big-serving American.

"I believe in miracles," Federer said, revealing that he thought his groin strain had ended his chances. "There could be rain, there could be all kinds of stuff.

"(I thought) just let him finish me off in style, and he didn't do that. I'm incredibly lucky tonight, today -- I don't even know what time it is."

Sandgren, achingly close to becoming the lowest-ranked player to beat Federer at the Australian Open, can count himself unlucky especially after a ball girl accidentally collided with him during the pivotal tie-breaker, which he lost. A bitterly disappointed Tennys Sandgren said it was "back to the drawing board". "Tired. Emotionally tired. Physically tired," he said after the gruelling encounter on centre court with the 38-year-old Swiss legend.

Federer has made heavy weather of reaching his 46th Major semi-final. He was two points from defeat by John Millman in a fifth-set tie-breaker in round three, and dropped a set against 67th-ranked Marton Fucsovics in round four.