Federer maintained his chances of winning a record eighth title -- and a first grand slam in four years -- when he saved three match points to finally overcome Marin Cilic 6-7 (4-7) 4-6 6-3 7-6 (11-9) 6-3 in the quarterfinals.
The Swiss coasted through four rounds this fortnight -- just what his body needed after missing chunks of the campaign with knee and back injuries -- but he was jolted by the Croatian's power and nearly exited in a cliffhanger of a fourth set.
There was, too, almost a second straight comeback on Centre Court, but an emotional Andy Murray held off Jo-Wilfried Tsonga 7-6 (12-10) 6-1 3-6 4-6 6-1. A blockbuster Sunday finale between Federer -- the record 17-time grand slam champion -- and Britain's Murray thus remains a possibility.
Federer was always wary of Cilic given he was swept aside in the 2014 U.S. Open semifinals in straight sets, and it turns out he was right to be cautious.
He hung on, though, getting help from his foe, to record a 307th grand slam victory, more than any other player in history, and land in the Wimbledon semifinals for the 11th time, tying him with Jimmy Connors for the Open Era lead. Federer's serve also came to life: 15 of his 27 aces arose in the fourth and fifth sets.
"It was an emotional win, always when you come back from two sets to love, but because of the season that I've had, it's wonderful," Federer said. "I was just very happy that I actually felt as strong as I did, mentally and physically when I was down two sets to love.
"Everything kind of went very quickly. Sometimes you feel when you're down two sets to love, the mountain to climb is huge, it's monstrous. Somehow everything went very quickly and I had great focus."
Federer faces a similarly big-serving rival in the last four, Milos Raonic, who beat Novak Djokovic's conqueror Sam Querrey 6-4 7-5 5-7 6-4, while 2013 champion Murray challenges 2010 finalist Tomas Berdych, a 7-6 (7-4) 6-3 6-2 winner over maiden grand slam quarterfinalist Lucas Pouille.
Cilic and his Wimbledon-winning coach Goran Ivanisevic will feel it should have been him appearing in the semifinals instead. A disgruntled Ivanisevic declined an interview request about half an hour after the classic concluded.
On his first match point at 5-4 in the fourth set, Cilic sent a second-serve return long. Federer saved another match point at 6-5 with an ace and then, with the 27-year-old holding a third match point at 7-6 in the tiebreak, the ninth seed's second-serve return found the net. As good as Federer's second serves were, Cilic would have expected to put at least one of the returns in play.
"I would say obviously in those situations, slight hesitation comes into your body," said Cilic, whose sole major success was that 2014 title in New York. "Legs start not to move, so you have to actually try to focus about the game that you need to play rather than the occasion.
"In those couple of occasions, especially match point in the tiebreak, and even one before on 5‑4, I believe, I had pretty make-able returns on second serves. That was pretty much a shame.
"Looking at my game during the day I played, I was winning a lot of points when I was being aggressive. Looking now, I would go a bit bigger on those shots."
At 8-8, adding to his woes, Cilic struck a double fault; Federer didn't hit one the entire afternoon.
Federer certainly has lost a step in his advanced tennis years but that doesn't mean he's slow. Far from it. And at 9-9, he scampered to his forehand corner to retrieve a Cilic backhand drive down the line. His forehand reply stayed low and skidded, making life awkward for Cilic, who proceeded to send his forehand wide.
Federer converted on his fifth set point and registered the lone break of the decider at 4-3 when Cilic's forehand went wide. The pro-Federer crowd on Centre Court erupted.
For the 10th time in his career and third occasion at Wimbledon, he was victorious when trailing 2-0 in sets.
If much of the drama unfolded in the fourth set, Federer's rally truly started when he escaped from 3-3, 0-40 in the third. He broke in the ensuing game.
Federer won't need to be told of the danger Raonic presents. His serve is even more potent than Cilic's, he is a more seasoned competitor and the Canadian -- formerly guided by Federer's current coach Ivan Ljubicic -- topped Federer in their lone meeting this year in Brisbane in January. Had he not succumbed to injury, Raonic might have defeated Murray in the Australian Open semifinals rather than lose in five sets.
He is sure to be less frazzled than when he confronted Federer in the Wimbledon semifinals two years ago. Back then, dropping serve in the opening game of the match set the tone and Federer cruised 6-4 6-4 6-4.
"I've improved," said sixth seed Raonic, now co-coached by three-time Wimbledon champion John McEnroe
. "I know what I need to do on court better. I know how to sort of turn things around to get them on my terms. I know what I'm looking for.
"I'm happy that I have another shot at him."
Murray led the flashy Tsonga 12-2 in their duels but all five of their grass-court contests were close. Wednesday was no exception, although when Murray claimed the tight first set -- Tsonga led 6-4 in the tiebreak -- and romped in the second, it had the air of concluding in three.
In a pulsating end to the fourth set, Murray broke for 4-2 but was broken immediately. Tsonga saved three break points for 4-4 -- two with stunning backhands, his weaker side -- and rode the momentum to force a fifth by depositing winners from seemingly every position on the court.
Murray, who lost only once before at a major when leading by two sets -- at his first one 11 years ago at Wimbledon -- was creaking. He stared at a break point to start the fifth, yet a Tsonga slip contributed to the 2008 Australian Open finalist putting a backhand into the net, much to the crowd's relief.
After winning the game the fired up Scot incredibly mouthed
to his box, "No way I'm losing this match," and so it proved as Tsonga quickly trailed 4-0.
"I was definitely tested a lot today," said Murray. "Probably the hardest match. I think it can give you a bit of confidence. It can help to go through games and stages in matches that are challenging.
"If you're in that position in the next couple of matches, you know you've been there. So I'm hoping it helps me the next couple of rounds."
Murray's tilt with Berdych not only pits the two players -- who have clashed on court
in the past -- head-to-head but the Czech against Murray's coach, Ivan Lendl. Berdych attempted to hire a then available Lendl near the end of 2014 but was rebuffed.
Lendl rejoined Murray last month after they parted company in March 2014.
"I approached Ivan when he stopped with Andy first time," Berdych said. "He basically says that he doesn't have the time and he don't want to be involved in tennis. Then he come back to Andy. So that's how it is."