The 2013 MLS Supporters' Shield winners were brushed aside 4-1 by the Whitecaps at BC Place with Scottish veteran Kenny Miller netting a double, while Sebastian Fernandez and Pablo Morales were also on the scoresheet.
The Red Bulls pulled a late goal back courtesy of Bradley Wright-Phillips but the damage had already been done leaving Petke to wonder what could have been different.
"The wrong one. And it's on me," Petke said when asked what his side's approach to the game was.
"I got it completely wrong. It comes down to me. That's all."
When quizzed further, Petke added: "What can I elaborate on? My gameplan obviously was wrong. Elaborate? What do you want me to elaborate on?
"The whole focus was for the first game the whole preseason and week leading up with the result obviously I got it wrong."
Thankfully for Petke, the Red Bulls get the opportunity to atone for that opening round disaster when they host the Colorado Rapids next weekend.
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