Despite not expecting any great showing at Monza, Eric Boullier says it is "hard to take" as McLaren yet again spent a Sunday outside the points.
The Woking team, powered by newcomers Honda, were predicting a tough weekend in Italy and that's exactly what they got.
While Jenson Button briefly ran inside the top ten in the opening laps, he slumped to 14th place, a lap behind race winner Lewis Hamilton.
As for his team-mate, Fernando Alonso retired six laps from the chequered flag with a loss of power.
Speaking about the team's weekend, Racing Director Boullier said: "We always knew that Monza and Spa-Francorchamps would be among the least well-suited circuits for our car, and so it proved at both venues.
"Here in Italy, we've come away with nothing to show for our efforts, and obviously that's hard to take for all concerned.
"It's been a stressful few days for us – that's probably been as obvious from the outside as it's been painful on the inside – but we'll now return to Woking and Sakura and continue the hard work in an effort to claw our way back to the front."
Looking ahead to the next race on the calendar, the Singapore GP, the Frenchman is at least hoping for a bit less pain on the street circuit.
He added: "We aren't predicting great things for the next race, Singapore, but we're hoping that that street circuit's characteristics will be slightly kinder to our car than Spa-Francorchamps and Monza have been."