London - Old world warriors Roger Federer and Novak Djokovic, with 23 Grand Slam titles between them, face the rookie ambitions of Milos Raonic and Grigor Dimitrov for a place in the Wimbledon final on Friday.
Seven-time Wimbledon champion Federer is the 32-year-old holder of a record 17 majors and Djokovic, 27, was 2011 champion at the All England Club and is a winner of six Grand Slam crowns.
Federer is about to play his 35th semi-final at a major while for Djokovic it will be number 23.
In stark contrast, Canadian eighth seed Raonic and 11th-seeded Bulgarian Dimitrov, both 23, are in unchartered waters.
With two-time champion Rafael Nadal and 2013 winner Andy Murray already out, just two of the big four, who have carved up 35 of the last 37 Grand Slam titles between them, remain.
And they remain the overwhelming favourites.
Federer, who was stunned in the second round last year 12 months after winning his seventh title, has a 4-0 career lead over Raonic, the first Canadian man in the semi-finals in 106 years.
Despite his desire to lift what would be a record eighth title, Federer insists he is happy to see a new breed coming through, even if they are already edging towards their mid-20s.
“It's just hard breaking through. The points, you fetch them from semis on, not really quarters anymore like it used to be,” he said.
“So it's hard I think for a youngster to win or be consistent over three, four, five matches in a row where the big points are.”
Federer will be the sentimental favourite on Friday against Raonic whose quarter-final win over Australian teenager Nick Kyrgios, the shock conqueror of Nadal, was brutally effective but far from pretty.
Many watching saw the performance, which produced 39 aces, 73 winners and just 20 points conceded off serve, as a throwback to the bad old days when grasscourt tennis was a one-shot shoot-out.
“Well, he's got a big serve. Clearly that's what is most visible when you see him play,” conceded Federer.
“It keeps him in the match. I've played him in some interesting places like Halle (on grass) where we basically didn't have any rallies whatsoever.”
Raonic insists his poor record against Federer will not be a factor when he becomes the first Canadian man since Robert Powell at 1908 to play in a Wimbledon semi-final.
“He's gotten the better of me all four times. But I haven't played him in more than a year and a bit, so I think I'm a different player,” he said.
“I've got in close with him in the past and I've found a lot of those things I can sort of pull away that give me a lot of belief that I can do this. I've got to step up and do it.”
Raonic has an extra incentive to make the final having seen compatriot Eugenie Bouchard reach the women's final on Friday, becoming the first Canadian player to make a major championship match.
Top seeded Djokovic was runner-up to Murray 12 months ago and he takes a 3-1 lead over Dimitrov into their semi-final.
Dimitrov, who will become the first Bulgarian man in the world top 10 next week, reached his first Grand Slam semi-final by defeating Murray in straight sets on Wednesday, a victory which finally allowed him to live up to the hype which had him nicknamed 'Baby Fed' in his junior days.
Transformed since hiring Australian coach Roger Rasheed, Dimitrov, who won the Wimbledon warm-up at Queen's Club last month, is getting known for his tennis rather than just being the boyfriend of Maria Sharapova.
“Fear is out of the picture,” he said of facing Djokovic.
The Serb said he will respect Dimitrov who has yet to lose on grass this summer.
“That says enough about his quality. I'm sure many people look at him as a potential Grand Slam winner. Maybe here, maybe in the Grand Slams to follow,” said the top seed.