World No.1 Serena Williams has maintained her perfect record over Agnieszka Radwanska to reach the final of the Rogers Cup in Toronto.
Williams will face Romanian Sorana Cirstea after downing fourth-seeded Radwanska 7-6 (7-3) 6-4, taking her unbeaten record against the Pole to six matches, a run that included a triumph in the 2012 Wimbledon final and, most recently, in the semi-finals in Miami this year.
Unseeded Cirstea toppled fourth-seeded Li Na of China 6-1 7-6 (7-5) in the other semi-final.
The victory over 2011 French Open champion continued a dream run for 27th-ranked Cirstea in the $US2.4 million ($A2.65 million) hardcourt tournament.
She also beat former world No.1s Caroline Wozniacki and Jelena Jankovic, as well as defending champion Petra Kvitova, en route to the final.
A tight first set saw Williams and Radwanska trade four service breaks, the American holding serve to force the tiebreaker.
Williams took control early in the tiebreaker, taking a 3-1 lead, and gave herself a triple set point with a cross-court winner for 6-3.
She needed just one of those set points, firing an ace to seal the set.
Williams went down a break to trail 3-1 in the second, finally regaining the break to level the set at 3-3 with a fierce overhead winner to end a long rally on her third break chance.
She saved a break point to hold for a 5-4 lead, and broke Radwanska in the last game with a backhand winner followed by a high forehand volley on match point to seal the victory in one hour and 51 minutes.
Cirstea was looking forward to her shot at Williams.
"I am really excited for what's happened this week and for tomorrow," she said. "Everything now is coming together for me."
The 23-year-old Cirstea cruised through the first set before Li jumped out to a 4-1 lead in the second.
Cirstea won five of the next seven games. She was unable to convert two match points in the 12th game as Li forced the tiebreaker.
In the decider, Li again gained the advantage, but Cirstea won six of the last seven points and clinched the semi-final victory on her third match point when a mistake-prone Li double-faulted.
"I'm happy with how I fought in the end and I'm really happy to finish the match in two sets," said Cirstea, who won her lone singles title five years ago at Tashkent.
Cirstea blasted 17 winners and converted four of seven break points in the 87-minute match, and was pleased that she was able to overcome some nerves and thwart Li's second-set rally.
