Sebastian Vettel has said he was surprised to see other cars be more competitive in wet conditions but was at a loss to explain why Ferrari were so far off the pace.
Vettel only qualified down in P8 and was 2.5 seconds slower than the record-breaking Lewis Hamilton, but engine penalties to Max Verstappen and Daniel Ricciardo ahead means the World Championship leader will start sixth in Sunday's race.
Team-mate Kimi Raikkonen, qualifying P7 but starting P5, also struggled for grip, yet Vettel had no idea what went wrong for Ferrari.
"I don't know," Vettel said when asked in the paddock why Ferrari struggled so much in wet conditions at Monza.
"I was surprised by how quick the others were and clearly we could not go the same pace.
"At this stage we don't know what happened but we will look at a couple of things and try to understand why.
"Nevertheless, it was an important day. Something didn't work and didn't come together but it is what is and we'll see what we can do tomorrow."
On Sunday's race, Vettel is not panicking too much as he still retains a lot of faith in the car he has and one that is sure to come to life again in dry conditions.
He added: "We have a good car so there is no need to be afraid.
"We are not where we wanted to be but we can make up a lot of ground. The car is quick and you can overtake here so it should be a fun race."