Having suffered two Grand Slam final defeats, Williams will go in search of her 24th major title in NY next month, while Osaka will look to defend her crown after early exits at Wimbledon and the French Open.
Serena Williams moved into the Rogers Cup semi-finals on Friday with a maiden career victory over Naomi Osaka in their first meeting since the American's infamous row with an umpire overshadowed last year's U.S. Open final.
The 23-time Grand Slam champion fired 12 aces and didn't face a break.
The Czech Marie Bouzkova, 91st World and qualifying, will be his opponent in Saturday's half: it has benefited from the abandonment after a set of the Romanian, ex-N.1 world, Simona Halep, embarrassed to a tendon d 'Achilles.More news: Opera Legend Placido Domingo Accused of Sexual Harassment by 9 Women
One comfort for Osaka is that she will return to the top of the world rankings next week.
Serena Williams celebrates match point in her Ladies' Singles second round match against Kaja Juvan of Slovakia during Day 4 of The Championships - Wimbledon 2019 at All England Lawn Tennis and Croquet Club on July 4, 2019, in London.
Osaka called Williams, 16 years her senior, her "tennis mom" prior to the match, to which Williams responded: "I'd say more or less tennis grandma".
"It was just a better match for me today", Serena acknowledged in her on-court interview. "I'm just overall a little bit better", Williams said.
"In the third set I told myself, Go big or go home, " the home hope said.More news: Struggling Phillies bring back Charlie Manuel as hitting coach
Victory in Canada sees Williams claim her first win against Osaka, who still leads their personal rivalry 2-1. "It s definitely not where I want to be, but I m getting there".
"I think in the first set we were kind of just serving it out, and then I was the one that - I don't even think I dipped. And she just played wonderful, which that's what she does". "And today I felt it more, so that's why I made a decision to retire", said Halep.
"So I know her game". The 19-year-old won a narrow quarter-final against Karolina Pliskova of N.3, 6-0, 2-6, 6-4.
The match, played in windy conditions, stayed on serve until Williams broke in the eighth game and the three-times champion went on to serve out the set.
The other semifinal will feature American Sofia Kenin (29th) against Canadian tennis star Bianca Andreescu (27th).More news: Astronomers Spot Unprecedented Flashes From Our Galaxy's Black Hole