MELBOURNE, Australia (AP) Roger Federer certainly knows what to expect in his Australian Open semifinal. And so does his opponent Stan Wawrinka.
There'll be no secrets in the all-Swiss showdown for a place in Sunday's final.
''I think him and Rafa (Nadal) best know my game. I've played him so much. Stan and I practiced so much together,'' Federer said. ''With Rafa, I only practiced once in my life, whereas with Stan, I can't even keep count anymore.''
The first of the men's semifinals will be played in the night session Thursday, following the women's semifinals which will feature three 30-somthings, and three Americans. Venus Williams, 36, will play CoCo Vandeweghe before Serena Williams, 35, takes on 34-year-old Mirjana Lucic-Baroni. Nadal will play Grigor Dimitrov on Friday night in the last of the semifinals.
Federer holds an imposing 18-3 lead in head-to-head encounters with Wawrinka. And, significantly, he has never lost to his compatriot on hardcourts.
While the pair have shared Davis Cup success and Olympic gold, that friendship must be temporarily put aside in the pursuit of the chance for another Australian title.
Four-time champion Federer will be playing his 13th semifinal at Melbourne Park, and the Australian Open is his most successful Grand Slam in match wins with 85.
But he's wary of Wawrinka, the 2014 champion, despite a remarkable start to 2017 after missing the second half of last year to recover from a knee injury.
''If someone would have told me I'd play in the semis against Stan, never would I have called that one for me,'' Federer said. ''For Stan, yes, but not for me. I honestly didn't even know a few days ago that he was in my section of the draw or I'm in his section.''
The 35-year-old Federer thought the quarterfinals was a realistic target for his Grand Slam comeback, but he has upgraded the expectations after hitting 65 winners past Germany's Mischa Zverev, who had upset top-ranked Andy Murray in the previous round.
Federer, who has his wife and four children with him in Australia, mused how one of his six-year-old twin girls asked when they could leave to go skiing in Switzerland. Maybe he can pacify an impatient daughter with an 18th Grand Slam singles title.
A look at the women's semi-finals on Thursday:
No. 13 VENUS WILLIAMS vs. COCO VANDEWEGHE
Unseeded American Coco Vandeweghe overpowered defending champion Angelique Kerber and French Open winner Garbine Muguruza in the past two rounds. Now she's playing Venus Williams, one of her tennis inspirations.
Vandeweghe said she must replace childhood admiration with ruthless instincts to attempt to reach her first Grand Slam singles final.
''It's a dream to play someone you grew up watching. To play an unbelievable player, future Hall of Famer in Venus, and to be on the court with her, I've only experienced it one time before,'' Vandeweghe said. ''But to do it at this stage of a Grand Slam is kind of crazy.''
It's the first semifinal appearance here for Williams in 13 years and, at 36, she's the oldest player to reach the last four of a Grand Slam since Martina Navratilova at 1994 Wimbledon.
''It's wonderful to be here to start the year out with this. I want to go further. I'm not happy just with this, but I'm just happy to be in the position to go further,'' Williams said. ''I have a lot to give to the game. I feel like I have a lot of great tennis in me. So, any time you feel that way, you continue. Why not? I have nothing to lose, literally.''
Williams won 6-4 6-3 on clay in Rome last year in her only previous meeting with Vandeweghe, who is 25.
''To have that thought that there's going to be at least one U.S. player in the final is great for American tennis,'' Williams said. ''I'm sure she's going to want to be in her first final. I'm going to want to be in only my second final here. So it's going to be a well-contested match.''
NO. 2 SERENA WILLIAMS vs. MIRJANA LUCIC-BARONI
So much for the new guard! A 35-year-old and a 34-year-old will play off for a place in the final.
It's so long since Serena Williams and Mirjana Lucic-Baroni played each other that Williams couldn't even recall the actual decade, let alone the year.
''It's really amazing. I'm so proud of Mirjana. I played her a decade ago, no, it was (almost) two decades ago,'' Williams said. ''No matter what happens, someone 34 or older will be in the final.''
Second round at the 1998 Wimbledon was their previous meeting, with Williams winning 6-3 6-0. Then their careers headed in dramatically different directions. Williams amassed 22 Grand Slam singles titles and a fortune in prize money and honors. Personal issues derailed the Lucic-Baroni's career, forcing an extended lay-off from the sport in the mid-2000s.
Lucic-Baroni didn't play a Grand Slam championship from the 2003 US Open qualifying rounds until 2010 Wimbledon as she dealt with issued she vowed to outline sometime in a book.
Struggling with left leg injuries, Lucic-Baroni underlined her grit to ease past U.S. Open finalist Karolina Pliskova in a three-set semifinal in which both players needed injury timeouts. She later dismissed concern that her fitness could be an issue against the most dominant player in the women's game.
''I'm really thankful to God that I was able to do this today. I started hurting mid-match, but I'm going to be fine,'' Lucic-Baroni said. ''I'll put on extra tapes and hope that keeps me together.''
On the longevity of both semifinalists, Lucic-Baroni said: ''Everybody is so strong now, they work harder and the recovery has got better. And maybe it's experience too.''