MONTREAL -- Finally beating her formidable younger sister may've been one more sign Venus Williams is on the way back to the top.

The five-time Wimbledon champion downed Serena Williams, the world's top-ranked player, 6-7 (2), 6-2, 6-3 in a fast-paced semifinal at the US$2.44 million women's Rogers Cup on Saturday.

It was 34-year-old Venus Williams' first win over her 32-year-old sister in more than five years, and will move her back into the world's top 20 after three seasons of injuries and illness.

She will play third-seeded Agnieszka Radwanska in the final Sunday.

Radwanska won a baseline battle 7-6 (1), 7-6 (3) over Ekaterina Makarova.

Venus Williams said her match with her sister may have felt like a final, but she has one more tough match to win.

"I definitely don't want to have a letdown and get out there (Sunday) and not play at least half as well," said Venus Williams. "I don't want to put any pressure on myself, but I want to go out there and perform just as well.

"It would mean a lot to me because I've been dreaming of winning a tournament at this level since I got back on tour. You try and you try. There are disappointments. One day you get a little closer. So this is my 'little closer' right now."

The unseeded Venus Williams, who uses medication, a vegan diet and extra rest to control Sjogren's Syndrome -- an auto-immune disease she was first diagnosed with in 2011 -- has had to grind out wins this week. She went to three sets for the fourth time in five matches.

Along the way, she knocked off sixth-seeded Angelique Kerber, 14th-seeded Carla Suarez Navarro and her top-seeded sister, the defending Rogers Cup champion and a winner last week at Stanford.

The win made Venus Williams the third woman to pass the US$30-million mark in career earnings after Serena Williams and Maria Sharapova.

She ended her sister's 14-match Rogers Cup winning run that dated back to wins at the 2011 and 2013 tournaments in Toronto. Serena Williams skipped the 2012 event.

Serena Williams hadn't lost to her older sister in five matches since 2009 in Dubai and still holds a 15-11 edge all-time.

"I think for both of us, what's so unique about the situation is that we're both very good players," said Venus Williams. "I think typically you may have some siblings, one is quite good, one is not as good so you kind of know what the result is.

"I think we both know when we walk out there, it's not like you're guaranteed a win. I think that's what makes it challenging for both of us."

Venus Williams started with a hot serve and took a 3-1 lead but the key game of the set came with Serena Williams serving at 3-3. Serena Williams hit six aces and two double faults before prevailing in an extended, back and forth battle.

The second set was all Venus Williams, who had two service breaks while her sister struggled with unforced errors.

Serena Williams made two errors to lose her serve and give her sister a 4-2 lead before serving out the third set.

Serena Williams had 19 aces and nine double faults, while the more consistent Venus Williams had six aces and two doubles faults.

"I don't think I played a great game today," said Serena Williams. "Let's just face it, I served well in the first set, but that was that.

"So I definitely need to go back and analyse it, figure out how to be more consistent."

In the evening semifinal, cracks began to show in Makarova's game late in an otherwise evenly played first set as she had to fight off two set points while trailing 4-5 and another at 5-6.

The tiebreak was a mess of unforced errors by Makarova. The Russian, who beat Radwanska in the fourth round at Wimbledon this year, played with her right thigh taped.

Makarova did well to fight back from down a break in the second, but Radwanska's relentless returning of balls from the baseline eventually wore her down. The two traded service breaks before going to another tiebreaker.

Serena Williams, who has 17 grand slam titles, has struggled in the majors this year. She was beaten in the fourth round at the Australian Open, second round at the French Open and third round at Wimbledon.

So she raised eyebrows when she said: "I haven't even been able to get to the quarter-finals of a Grand Slam this year. At this point, I'm really just looking forward to next year, to be honest."

She was quick to point out that didn't mean she's giving up on the U.S. Open at the end of August, where she is the two-time defending champion.

"I'm just saying I've had a really disappointing year, for me, especially in the Grand Slams," she said. "So I'm not going to put any pressure on myself.

"I almost feel like the pressure is lifted because I haven't performed the way I've wanted to. In a way, I don't feel a ton of pressure going into the Open. I almost feel like it's lifted. I look forward to next year because I don't have any points to defend at any of the slams."