Lewis Hamilton is predicting an "easy win" for his championship rival Max Verstappen on Sunday.
The Mercedes driver, whose deficit to Red Bull's Verstappen blew out to 5 points on Saturday, fell behind the top cars after making a poor start to the sprint race.
"The line between hero and zero is extremely fine," said Mercedes boss Toto Wolff.
"These days happen. When we as a team have a rough day, hardly anyone notices. But when the racing driver has one, you see it straight away."
The good news for Hamilton is that his Mercedes appears to have more pure pace than Verstappen on the high-speed Italian circuit.
However, Hamilton warned: "If I don't get past the two McLarens quickly, it will be an easy win for Max."
He is also concerned that, even on less favourable circuits for Red Bull, Verstappen continues to charge towards his first world championship.
"They bring upgrades every week," said the seven time world champion.
"They're constantly adding more performance to the car."
Red Bull's Dr Helmut Marko thinks Mercedes is struggling when hitting the highest speeds around the fabled Autodromo Nazionale di Monza.
"It was clear that Mercedes' engine was hitting the limiter on the straight lines, and we were competitive," he said.
"Our usual Monza problem is gradually going away," the Austrian told ORF.
"We never even thought about pole position, but what's even more encouraging is our speed in the race.
"Bottas had a brand new engine and still didn't pull away," Marko added.
"As we saw with Hamilton and Perez, overtaking is practically impossible. So if we get a good start, we can already start dreaming of another victory."