Hubert Hurkacz and Mate Pavic upset top seeds Wesley Koolhof and Neal Skupski on Wednesday at the National Bank Open Presented by Rogers.

The Polish-Croatian pair fired 14 aces to defeat the defending champions 6-7(2), 7-6(2), 10-5 and book their ticket to the Toronto quarter-finals. Koolhof served for the match at 6-5 in the second set before Hurkacz and Pavic mounted a comeback, with the 26-year-old Pole ripping a forehand return winner on break point to push the Dutch-British team to a second-set tie-break. 

Hurkacz and Pavic will next meet Nicolas Mahut and Vasek Pospisil or Kevin Krawietz and Tim Puetz. Koolhof and Skupski, who are No. 1 in the Pepperstone ATP Live Doubles Teams Rankings, were competing in their first match since collecting the Wimbledon title.

Second seeds Ivan Dodig and Austin Krajicek didn’t fare any better, falling 6-3, 7-6(4) to Marcelo Arevalo and Jean-Julien Rojer in their first outing as a pair since a second-round exit at Wimbledon.

In other doubles action, eighth seeds Santiago Gonzalez and Edouard Roger-Vasselin downed Tallon Griekspoor and Jiri Lehecka 6-2, 6-7(6), 10-6 to maintain their form following last week’s triumph in Los Cabos. The Mexican-French duo also won the ATP Masters 1000 event in Miami and in Marseille earlier this season.

Sander Gille and Joran Vliegen moved past Marcelo Melo and John Peers 7-6(6), 2-6, 10-7 and seventh seeds Marcel Granollers and Horacio Zeballos reached the last eight after Fabrice Martin and Andreas Mies retired at 4-4.