Montreal's Eugenie Bouchard was unable to continue her string of big wins at the Pan Pacific Open Thursday when she faced American star Venus Williams in the quarter-finals.
Bouchard called Williams a "legend."
"I watched her when I was younger," she said on the WTA's website. "She's a legend and a really great player. So I was really excited to play against her — but I didn't take my chances enough, and against a player like Venus you need to."
The 19-year-old Montrealer lost 6-3, 6-7, 6-3 to Williams in a three-hour match.
Williams, playing in the Tokyo tournament for the first time since 2009, broke Bouchard with a forehand down the line to go up 5-2 in the third set and held on to win the match at Ariake Colosseum.
"She played so well," Williams said. "She's going to be a great player -- she's already a great player -- and it was just a fight to the end."
Bouchard put Williams on notice when she built a 3-1 lead in the quarter-final, but Williams fought back to break her three times in their first meeting.
In the second set, Bouchard capitalized on her second set point, winning the tiebreak 7-4.
"I was just fighting until the end," Williams said. "It was disappointing to lose the second set, but to win the third set is the goal, so I'm happy."
Each player served a pair of aces and Willams recorded 35 unforced errors to 34 for Bouchard.
Bouchard had upset sixth-seeded Jelena Jankovic of Serbia 7-5, 6-2 on Wednesday, a day after ousting No. 8 Sloane Stephens of the U.S.
"I'm always disappointed to lose, I played some good matches here, but I always want to do better," Bouchard said. "I don't think I played as well as I can, but obviously Venus is a great player and she put a lot of pressure on me throughout the whole match. I never really felt in control on the court."
Bouchard, making her debut in the Tokyo tournament, is 46th in the world rankings.
Earlier, she said winning last year's junior Wimbledon title has given her confidence to compete at a higher level.
Williams will face Petra Kvitova in the semifinals. The seventh-seeded Czech beat Svetlana Kuznetsova 6-4, 6-1.
The American had ousted top-seeded Victoria Azarenka on Tuesday.
Kvitova of the Czech Republic defeated Madison Keys of the United States, 6-2, 6-2 while Kuznetsova of Russia beat Sorana Cirstea Romania, 7-6 (3), 6-1.
Elsewhere, Also, fourth-seeded Caroline Wozniacki beat Lucie Safarova of the Czech Republic 2-6, 6-3, 6-2 to set up a semifinal with fifth-seeded Angelique Kerber of Germany, who ousted second-seeded Agnieszka Radwanska of Poland 6-4, 6-4.
Wozniacki and Kerber are 3-3 head to head. Wozniacki won their semifinal at Indian Wells in March.