Hirvonen completed the stage in eighth place, 2.770 seconds off Sebastien Ogier's fastest time.
The Finn starts the Greek round of the World Rally Championship running fifth on the road, but remains adamant there is still a chance for him to take his first win of the season for Citroen.
"The rally hasn't even started yet," said Hirvonen, "and we haven't seen any of the stages in competition - anything can happen.
"I don't know what happened in qualifying, it was really strange. It felt OK. I got to the end and thought the stage had gone quite well, but the time was not good.
"I tried to be clean, maybe I was too clean."
Hirvonen tested the Citroen again at the start of the week, running for half a day close to the event's Loutraki base.
"I found a good set-up in this test," he said. "I am confident with the car. I have no excuses for this morning, but I still believe in the set-up I found at the test, I believe it's the right one and we're going to stick with it.
"Sure, it's not going to be easy running in this position [on the road] today, but like I said, anything can happen still. Let's see."
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- Sebastien Ogier