JOIN USRafael Nadal recovered from a slow start, overcoming Marin Cilic 2-6, 6-4, 6-4 as the Spaniard's chase for a long-sought ATP Masters title on hardcourt heated up.
The world number one reached the semifinal in Toronto and will next face Russian Karen Khachanov, who beat Robin Haase 6-3, 6-1. Nadal last won a title at this level on cement in 2013.
"It was a very important match for me," Nadal said.
"Being in semifinal is great news at the start of the hard court season."
Stefanos Tsitsipas saved two match points to beat defending champion Alexander Zverev in their quarterfinal contest 3-6, 7-6 (13/11), 6-4.
The Greek teenager, who turns 20 on Sunday's final day, defeated his third straight top 10 opponent at the tournament after knocking out Dominic Thiem in the second round and 13-time major winner Novak Djokovic in the third.
Tsitsipas will next face Wimbledon runner-up Kevin Anderson, who beat Grigor Dimitrov 6-2, 6-2.
"I'm confused now, is this real?" 27th-ranked Tsitsipas said after completing his prestige hat-trick of upsets.
Tsitsipas rallied from a set and 5-2 down to turn the tables on Zverev, who had been bidding for a fourth Masters 1000 title.
Tsitsipas broke in the ninth game of the second on the way into a tiebreaker, where he calmly converted on his fifth set point after saving two match points for the second-seeded Zverev.
Tsitsipas then salvaged four break points for 2-1 in the third, he traded breaks with the German and saved another trio of break points for a 5-4 lead.
He completed the victory after nearly two and a half hours on Zverev's sixth double-fault.
Anderson's sweep past reigning ATP World Tour Finals champion Dimitrov was a rematch of their 2014 quarterfinal duel in Canada when Dimitrov claimed one of his six wins against the South African.
"It definitely was a great match today. I felt I played really well right from the beginning," Anderson said.
Halep topples Garcia
World number one Simona Halep punched her ticket to the semifinals of the WTA Canada tournament for the fourth straight year, cruising past France's Caroline Garcia 7-5, 6-1.
The 26-year-old Halep battled through a difficult first set, then easily won the second in a rematch of last year's quarterfinal contest with Garcia which was also won by the Romanian.
Halep moves on to the final four where she will face Aussie Ashleigh Barty, who ousted giantkiller Kiki Bertens of the Netherlands in straight sets 6-3, 6-1.
US Open champion Sloane Stephens was just as ruthless as Barty in her quarterfinal as the third-seeded American made the semifinals for the second straight year, seeing off Anastasija Sevastova of Latvia 6-2, 6-2.
Stephens will face defending champion Elina Svitolina, who came back from an 0-4 deficit in the first set to eliminate Elise Mertens 7-5, 6-3.