John Isner and Bernard Tomic claimed first-round wins at the Rogers Cup as Nick Kyrgios suffered a shock loss.
Isner and Tomic were joined as winners by Jack Sock and Grigor Dimitrov, while Kyrgios slumped to a defeat.
Kyrgios was stunned by teenage Canadian wildcard Denis Shapovalov, who won in three sets.
ISNER, TOMIC PROGRESS AS KYRGIOS LOSES
American Isner recovered from a slow start, firing down 15 aces in a 4-6 6-3 6-2 win over Dudi Sela.
On a warm day in Toronto, Tomic was also a winner, beating Alejandro Gonzalez 6-4 7-6 (7-1).
Tomic's Australian countryman Kyrgios, however, had no such luck, slumping to a 7-6 (7-2) 3-6 6-3 defeat to 17-year-old world number 370 Shapovalov.
KYRGIOS THE ONLY SEED TO FALL
Kyrgios, the 11th seed, was the only seeded player to depart.
The only other seed in action was Sock, who was far too good for fellow American Denis Kudla 6-2 6-2.
DIMITROV FIGHTS BACK, POLANSKY CRUISES
Dimitrov, who has endured a below-par year, fought his way past Yuchi Sugita 5-7 7-6 (7-5) 6-4.
The Bulgarian trailed 5-2 in the second-set tie-break before winning five straight points.
Canadian Peter Polansky lost no points on serve in the third set of his 4-6 6-3 6-0 win over Tim Smyczek.
KYRGIOS PAYS TRIBUTE TO SHAPOVALOV
Kyrgios was full of praise for Shapovalov, the Wimbledon junior champion, but was nursing an injury.
Nick Kyrgios comes into press wth a big bag of ice strapped to his knee. "He played great and he earned it." pic.twitter.com/wD8eyzhQyu-- Rogers Cup Toronto (@rogerscup) July 26, 2016
WAWRINKA, BERDYCH TAKE CENTRE STAGE
"[Nick] told me I'm a great tennis player and that he wishes me the best." -Shapovalov on the respect he got from @NickKyrgios.-- Rogers Cup Toronto (@rogerscup) July 26, 2016
Swiss second seed Stan Wawrinka begins his campaign with a clash against Mikhail Youzhny. Tomas Berdych is set to be tested by talented Croatian Borna Coric.