Serena and Venus Williams will clash in the semi-finals of the Montreal WTA tournament after the American sisters battled through tough three-setters in the quarter-finals on Friday.
World number one Serena outlasted Caroline Wozniacki to clinch a 4-6, 7-5, 7-5 victory while Venus also came from a set down to beat Spanish 14th seed Carla Suarez Navarro, the third round conqueror of Maria Sharapova, 4-6, 6-2, 6-3.
Serena will take a 14-10 career lead over her older sister into Saturday's match.
The 32-year-old has won their last five meetings while Venus's most recent win was in Dubai in 2009.
Serena, who lifted her third Canadian crown last year when the tournament was held in Toronto, battled back from a set and a break down to claim victory over Wozniacki in two hours and 41 minutes.
"When you play someone like Caroline or other opponents, you know your match might be a little longer than normal," said Williams, who extended her career head-to-head record over the 13th-ranked Dane to 7-1.
"You go in there thinking, this is not going to be routine. You have to be ready."
Wozniacki, a former world number one who is seeded 11th, claimed her only victory over the US star in the quarter-finals at Miami in 2012.
Wozniacki had been riding an eight-match winning streak, including a title in Istanbul in July.
"It was really the small things that I did out there today," added Williams.
"She came up with quite a few big serves when she needed to. It could have gone both ways."
Williams claimed her fourth title of the year at Stanford on Sunday, but she has disappointed in the majors this year, failing to add to her cache of 17 Grand Slam titles.
She'll get a last chance of 2014 to do so at the US Open, which starts in Flushing Meadows on August 25.
As she has in many of her recent matches, Williams got off to a slow start against Wozniacki and the Dane was soon up 6-4, 4-2.
With the aid of an improved serve -- which yielded a total of 15 aces in the match, Williams began to assert herself.
"I am definitely fit," Williams said. "I feel like I am ready to go the long haul. I needed to feel that and get some three-set wins under my belt."
Wozniacki twice recovered a break in the third set before Williams finally closed out the match.