Luck ran out for world No. 1 Iga Swiatek on Saturday as the top seed fell 6-2, 6-7(4), 6-4 to Jessica Pegula in a semi-final shock at the WTA Montreal event.
Defeat in two and a half hours came a day after Swiatek had won her 50th match of the season.
Despite the loss, the Pole will remain atop the WTA rankings with the US Open starting in just over a fortnight in New York.
Pegula, who grew up just over the border in Buffalo, NY, will play her third career 1000-level final against Elena Rybakina, winner over Daria Kasatkina, on Sunday.
The player from a billionaire family had her troubles in going through, serving for victory leading a set and 5-4 and then holding a 4-2 margin in the tiebreaker before Swiatek forced a deciding set.
Swiatek had won five of their six previous matches.
“No better way to earn it, I love playing here, I really do,” the winner said.
“Being born in Buffalo, I’m right on the border of Canada, so I feel you guys are my fans even though I’m American.”
Pegula survived eight breaks of serve while breaking Swiatek 11 times as the top seed completely lost her way.
The American will play her second final of the season after Doha in February.
Pegula can become the first American to win the WTA 1000 tournament in Canada since Serena Williams in 2013.
