Ivan Dodig made a triumphant return from injury with a 6-4 6-7 6-3 upset victory over 10th seeded American John Isner in the opening round of the Rogers Cup after the Croat missed nearly three months with a broken rib.
Dodig, back on court for the first time since retiring in the opening round of the French Open, showed no sign of rust as he consigned Isner to a second consecutive first round loss.
Twice a winner this season, Isner got his North American hard court campaign off to a confident start by picking up a ninth career title two weeks ago in Atlanta.
However, the big-serving American has been misfiring ever since.
Despite the stormy weather, the two other seeds in action on Day One, Marin Cilic and Jo-Wilfried Tsonga, progressed into the second round.
Cilic continued his domination of Denis Istomin taking a 6-2 4-6 7-5 decision as Tsonga survived an early challenge from Eduard Roger-Vasselin before easing to a 7-6 6-1 win.