Max Verstappen won the race after starting second, taking advantage of a safety car and an error from George Russell during a race which featured a chaotic mix of both a wet and dry track.
Team-mate Sergio Perez on the other hand commemorated his new contract in the worst way possible as a self-inflicted DNF followed a second successive Q1 exit.
When the Mexican's new contract was announced, Horner expressed Red Bull's belief in the driver.
Horner said: "We are confident in Checo and look forward to his return to proven form and performance", although the driver is yet to deliveron that backing.
What did Horner say about Perez?
Perez had another weekend to forget in Canada. His slide into the barrier when already running out of the points left his rear wing a mess and his spirits crushed.
Whilst he was not to blame for the previous crash in Monaco, there was no hiding place for the 34-year-old in Montreal.
Horner told Sky Sports: “It’s a horrible weekend for Checo [Perez].
"Obviously we’ve picked up some damage so, yeah he’ll need to come back strong in Barcelona. Thankfully, Ferrari had a shocker today so didn't get any points, so that let us off the hook somewhat."
Ferrari's disastrous double DNF means they have lost ground on Red Bull in the constructors' championship, but with the pack continuing to close up, Perez will need to pull his weight to help the reigning champions defend their title.
Horner continued: “we got away with it today but you know we need Checo back up there where he was at the beginning of the year, from Barcelona onwards.”
“I think Checo, what we see with him time and time again, you think he’s on the ropes and then he bounces back," Horner added, on a more positive note.
"He’s a tough racer, he’s a tough character and I think, it hurts him more than anyone else and he’ll be determined to come back and show everybody the form we know he’s capable of and showed in the first four races of this year, in Barcelona.”