MELBOURNE, Australia — A post-millennial through and through, Stefanos Tsitsipas sounded as excited about doubling his YouTube channel's followers to more than 30,000 within a few hours — "Oh, my God. Really?!" — as he was about becoming the youngest Grand Slam semifinalist since 2007.
Ah, to be 20, emerging as possibly the Next Big Thing in tennis and getting the opportunity to promote your travel vlogs.
"Guys," he urged folks watching the Australian Open on Tuesday in person or on TV, "if you haven't subscribed, please subscribe."
Lest anyone get the idea that Tsitsipas' stunning victory over Roger Federer at Melbourne Park was a fluke, he followed it up by beating No. 22-seeded Roberto Bautista Agut of Spain 7-5, 4-6, 6-4, 7-6 (2) to become the first player from Greece to reach the final four at a major tournament.
"I knew that win against Federer was important, played a huge role in my image — like, who I am," said Tsitsipas, who eliminated the two-time defending champion in the fourth round Sunday. "But I knew that the biggest challenge was today's match, that I can prove myself once again."
Next for Tsitsipas will be 17-time major champion Rafael Nadal, who stopped the career-best run of another up-and-coming member of the sport's new generation, 21-year-old American Frances Tiafoe, by dominating him 6-3, 6-4, 6-2. Nadal saved the only two break points he faced and broke Tiafoe the first time he served in each set.
In women's action, unseeded 25-year-old Danielle Collins of the U.S. reached her first Slam semifinal with a 2-6, 7-5, 6-1 victory against Anastasia Pavlyuchenkova of Russia. Collins was an NCAA champion at the University of Virginia who began this tournament with an 0-5 record at majors and now has strung together five victories in a row, including over 2016 champion Angelique Kerber.
Collins put aside a poor start Tuesday, including dropping a 16-minute, 28-point, 11-deuce second game to completely dominate the final set, which she opened by grabbing 20 of 23 points.
She'll now face two-time Wimbledon champion Petra Kvitova, who is back in the semis at a major for the first time since she was stabbed during an attack at her home in December 2016.
"I didn't really imagine being back," a teary Kvitova said after defeating No. 15 Ash Barty of Australia 6-1, 6-4.
"I'm calling it my 'second career,'" Kvitova said. "So it's the first semifinal of the 'second career.'"
She hadn't been this far at any Slam since Wimbledon in 2014, and at Melbourne since 2012.
Cheered on by a loud, flag-waving contingent of Greek fans inside and outside Rod Laver Arena, Tsitsipas displayed his varied toolbox, producing 22 aces, 30 more winners than unforced errors (68-38) and a nose for getting to the net.
It was a terrific encore to what he did against his idol, the 37-year-old Federer, a result that left Tsitsipas unable to sleep.
Tsitsipas was down a break in the first and third sets before turning both around against Bautista Agut, whose own thrill-ride to the quarterfinals included victories over Andy Murray, a three-time major champion, and Marin Cilic, the 2014 U.S. Open champion and the runner-up to Federer at Melbourne Park a year ago.
"Well, he's a good player, no? He's very complete. He has a good forehand and backhand. He's serving well," Bautista Agut said about Tsitsipas. "I think he knows the game. He knows how to play."
That's why his peers voted him the 2018 Most Improved Player.
And why he's already in the Top 20, seeded 14th in Australia.
Tsitsipas recently was asked what his goal was for this season. The reply: reaching the semifinals at a major. Well, we're all of three weeks into 2019 and that box is checked.
So is he satisfied?
"That's like the starting point to go deeper," Tsitsipas replied. "That's like the minimum, I would call it."
No man as young as Tsitsipas had been this far at any Grand Slam tournament since Novak Djokovic at the 2007 U.S. Open or at the Australian Open since Andy Roddick in 2003.
"It all feels like a fairy tale, almost. I'm just living the dream, living what I've been working hard for," said Tsitsipas, who dropped his racket, fell on his back and covered his face with his hands at match's end. "I mean, I feel a bit emotional but not too much because I know I worked hard to get here."
Seated in his courtside guest box were his parents — his father is his coach; his mother was a tennis player in the Soviet Union — and two siblings, along with Patrick Mouratoglou, who coaches Serena Williams and serves as a mentor to Tsitsipas.
Before introducing them, and other members of his entourage, to the audience during his post-match interview, Tsitsipas discussed his love of "cinematography, filmmaking, photography" and the way the YouTube videos he began making last year serve as a creative outlet.
Later, at his news conference, Tsitsipas expanded on what he gains from his hobby.
"When I'm desperate sometimes, when I feel down, I do these videos. I actually feel better," he said. "It makes me realize that tennis is not the most important thing in life, that we all have some other talents that we don't know about. It kind of makes me more relaxed."