Players react to Federer's comeback win: "Unbelievable"

Roger Federer's great escape at the Australian Open, saving seven match points for a quarterfinal victory captured the attention of the locker rooms as much as anywhere else.

Federer came back from two sets to one down to beat Tennys Sandgren, 6-3, 2-6, 2-6, 7-6 (8), 6-3. He was dealing with a groin injury during the second set that affected his play for most of the match.

"What he did was amazing. He showed me he's one of the best players of all time. I mean, he never gives up. When it matters the most, he's focused and he plays his best tennis," said Novak Djokovic, who followed Federer on court and won his quarterfinal against Milos Raonic in straight sets.

Raonic, who has frequently been injured during his career, also noted Federer's effort—first, that he kept playing and then won.

"[The] important thing is you know it's something you can't make worse," Raonic said. "I've played here when I was in the semis against Andy, I got hurt and ... I finished the match.

"Roger had a chance today, he created a chance for himself. It was impressive for Roger to be able to turn it around the way he did."

Simona Halep, who won her semifinal over Anett Kontaveit the following day, said the performance could provide players with inspiration.

"I saw that. I watch him, yeah," she said. "It was unbelievable, actually, and the way that he accepted, that he's not fit, and just fought for every ball. I have to learn from that."

The Swiss also went five sets against John Millman, coming from 8-4 down in a match tiebreak in the third round at the Australian Open.

Federer will meet Djokovic for the 50th time for a spot in the Australian Open final.