When the self-styled "old guy" of tennis stood match point down at 4-5 30-40 in the fourth set, it looked like he would be sucked deeper into the mire.
When the 34-year-old stood another match point down two games later, the hole was getting wider.
When the Swiss stood yet another match point down at 6-7 in the tiebreak, he was hanging on by his fingernails.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
However, Federer has not won a record 17 grand slam titles for nothing and he showed what makes him the ultimate champion as he performed not one, not two, not three but four great escapes during a nerve-shredding Wimbledon quarter-final.
It was little wonder that the earth shook under Centre Court as 15,000 hollering fans jumped to their feet to greet Federer's astonishing 6-7(4) 4-6 6-3 7-6(9) 6-3 victory that kept alive the Swiss maestro's dreams of an eighth Wimbledon trophy.
"When you're down two sets to love, three-all, love-40, it's a moment when it's not in your control anymore," Federer said after setting up a semi-final with Canadian sharp-shooter Milos Raonic.
"There were many more match points in my mind than just three today. But I fought, I tried, I believed. At the end I got it done."
How he got it done defied logic.
"I cannot believe Roger Federer won that match. Unbelievable tennis. How did he get out of that?" gushed American great and Raonic's coach John McEnroe.
"You've got to love the courage that he is able to find a way to do that, that is a killer loss."
UNBELIEVABLE FEELING
A killer loss for Cilic, maybe, but a shot in the arm for Federer who came to Wimbledon saying even he "didn't know how my body will hold up" having not played a best-of-five-setter since pulling out of last month's French Open with a back injury.
"To win a match like this, to test the body, to be out there again fighting, being in a physical battle and winning it is an unbelievable feeling," the third seed said after surging back from two-sets down for the 10th time in his career
"My legs were there, my back was there, serving was key. Mentally this is going to give me a hell of a boost. I am ecstatic that I was able to come through... somehow."
"Somehow" was the correct assessment as the most gifted shotmaker in tennis was found wanting in the opening two sets against a man he had beaten in five of six previous meetings.
His silky shots were in short supply as Cilic threatened to "blow away" Federer, just as the Croatian had done en route to the U.S. Open title two years ago.
"I couldn't read his serve. It wasn't going well for me," summed up Federer as his hopes of ending a four-year barren run at the slams looked to be in jeopardy.
But he hung on for dear life, hoping against hope "to get a bit lucky".
A deluge of lucky breaks started flowing Federer's way from midway through the third set.
At 3-3, three backhand errors from Cilic allowed to Federer to stay alive from 0-40 down.
At 2-1 down in the fourth set, Federer survived two more break points as the ninth seed failed to take advantage of the Swiss's second serves, misfiring both returns.
Then came the heart-stopping match points, and yet again all Federer did was fire down some soul-destroying deliveries -- as on each occasion Cilic never got the ball back into play.
Once Federer had bagged the "crazy breaker" on his fifth set point, it took him only another 33 minutes to subject Cilic to the most painful defeat of his career -- his 27th ace finishing off the job.
"I don't remember coming back from two sets to love here. This is huge for me, my season, my career," Federer said after securing his passage to an 11th Wimbledon semi-final.
(Reporting by Pritha Sarkar, Editing by Ken Ferris)
