World number 32 Mirnyi of Belarus never lost his calm against fifth-seed Hewitt in the second round match.
“I was confident because when you find yourself in a three-set situation with a top player, it’s an indication you are doing something well,” said Mirnyi, who won his first title earlier this year in Rotterdam.
Mirnyi will face Thailand’s Paradorn Srichaphan in the third round after the 11th seed beat Canada’s Daniel Nestor 7-5, 6-4.
Wildcard Simon Larose, the only Canadian left in the event, continued his winning form with a 7-6, 1-6, 7-5 victory over Argentina’s Jose Acasuso.
Larose, ranked 314 in the world, upset three-time French Open champion Gustavo Kuerten in the first round of the $2.45 million tournament.
The Quebecer took advantage of an Acasuso error to survive a match point at 5-4 in the final set. He reeled off the next three games to set up a daunting showdown against top seed and world number one Andre Agassi.
Agassi has yet to drop a set in Montreal but had an early scare against Russia’s Nikolay Davydenko.
Davydenko served on a set point, but the American fended it off and then cruised to a 7-6, 6-2 win.
Second seed Juan Carlos Ferrero strolled into the third round with a swift 6-3, 6-4 win over Morocco’s Younes El Aynaoui.
He next meets Slovakia’s Karol Kucera, who edged out Netherland’s 15th seed Martin Verkerk 7-6, 7-6.
Third seed Roger Federer saw off Britain’s Greg Rusedski 6-4, 6-3 and the Swiss will now face Spain’s Tommy Robredo, who made short work of Zimbabwe’s Wayne Black 6-0, 6-2
Britain’s Tim Henman lost 6-4, 6-4 to Argentina’s David Nalbandian who will play American Vincent Spadea, winner against France’s Arnaud Clement 6-0, 6-7, 7-5.
France’s only remaining hope, ninth seed Sebastien Grosjean, won a baseline battle against Paraguay’s Ramon Delgado 6-3, 6-2.
Grosjean next meets sixth seed Andy Roddick, who defeated Argentina’s Juan Ignacio Chela 7-6, 6-2.
Wednesday’s results (prefix number denotes seeding):
Second round: 1-Andre Agassi (US) beat Nikolay Davydenko (Russia) 7-6 (7-3), 6-2; 2-Juan Carlos Ferrero (Spain) beat Younes El Aynaoui (Morocco) 6-3, 6-4; 3-Roger Federer (Switzerland) beat Greg Rusedski (Britain) 6-4, 6-3; Max Mirnyi (Belarus) beat 5-Lleyton Hewitt (Australia) 7-5, 6-7 (4-7), 7-5; 6-Andy Roddick (US) beat Juan Chela (Argentina) 7-6 (7-2), 6-2; 8-Rainer Schueuttler (Germany) beat Yevgeny Kafelnikov (Russia) 6-1, 6-4; 9-Sebastien Grosjean (France) beat Ramon Delgado (Paraguay) 6-3, 6-2; 10-Jiri Novak (Czech Republic) beat James Blake (US) 7-6 (7-5), 6-3; 11-Paradorn Srichaphan (Thailand) beat Daniel Nestor (Canada) 7-5, 6-4; Karol Kucera (Slovakia) beat 15-Martin Verkerk (Netherlands) 7-6 (10-8), 7-6 (7-3); 16-Tommy Robredo (Spain) beat Wayne Black (Zimbabwe) 6-0, 6-2; Karol Beck (Slovakia) beat Mariano Zabaleta (Argentina) 6-1, 6-1; Sebastien Larose (Canada) bt Jose Acasuso (Argentina) 7-6 (7-5), 1-6, 7-5; Vince Spadea (US) beat Arnaud Clement (France) 6-0, 6-7 (5-7), 7-5; Feliciano Lopez (Spain) beat Paul-Henri Mathieu (France) 6-4, 3-6, 7-5; David Nalbandian (Argentina) beat Tim Henman (Britain) 6-4, 6-4.
CLIJSTERS CRUISES
LOS ANGELES: Top seed Kim Clijsters continued her solid play through the summer hardcourt season with a comfortable 6-1, 6-1 victory over France’s Emilie Loit in the second round of the JP Morgan Chase Open on Wednesday.
In stark contrast to Clijsters, fifth seed Jelena Dokic of Yugoslvia remains mired in a run of poor form and was beaten 4-6, 7-6, 6-3 by Russian prospect Svetlana Kuznetsova.
Other seeds fared better, however, including three-time champion and number two here Lindsay Davenport, who wasted little time handing out a 6-3, 6-1 thrashing to Austria’s Barbara Schett.
Eighth seed Amanda Coetzer, number 10 Meghann Shaughnessy and number 16 Francesca Schiavone also advanced to the last 16.
Two other players scored upset victories, with Spain’s Virginia Ruano Pascual defeating ninth seed Elena Dementieva 6-3, 5-7, 7-5 and Australia’s Nicole Pratt edging out 12th seed Eleni Daniilidou of Greece 6-2, 6-7, 6-3.
Fourteen-year-old Viktoriya Kutuzova of Ukraine continued a dream start to her career when she moved into the third round of her first event on the WTA Tour after her opponent, Alexandra Stevenson, retired with a right shoulder strain.
Kutuzova, who led 6-3, 3-3 when the 15th seeded American withdrew, next faces fourth seed Ai Sugiyama of Japan.
Wednesday’s results:
Second round: 1-Kim Clijsters (Belgium) beat Emilie Loit (France) 6-1, 6-1; 2-Lindsay Davenport (US) beat Barbara Schett (Austria) 6-3, 6-1; Svetlana Kuznetsova (Russia) beat 5-Jelena Dokic (Yugoslavia) 4-6, 7-6 (7-5), 6-3; 8-Amanda Coetzer (South Africa) beat Aranxta Parra (Spain) 6-1, 6-1; Virginia Ruano Pascual (Spain) beat 9-Elena Dementieva (Russia) 6-3, 5-7, 7-5; 10-Meghann Shaughnessy (US) beat Fabiola Zuluaga (Colombia) 3-6, 6-3, 7-6 (7-4); Nicole Pratt (Australia) beat 12-Eleni Daniilidou (Greece) 6-2, 6-7 (5-7), 6-3; Paola Suarez (Argentina) beat 13-Elena Bovina (Russia) 2-6, 7-5, 7-5; 16-Francesca Schiavone (Italy) beat Tamarine Tanasugarn (Thailand) 5-7, 6-3, 6-0; Rita Grande (Italy) beat Angelique Widjaja (Indonesia) 6-4, 1-6, 6-4; Viktoriya Kutuzova (Ukraine) beat 15-Alexandra Stevenson (US) 6-3, 3-3 — retired.—Reuters/AFP