McLaren got off to a strong start at Monza on Friday morning, despite testing a rear wing that looked more suited to a high-downforce track.
While many rivals were running more conventional for Monza 'tea-tray'-style wings for the Autodromo's long straights, observers were surprised when the MP4-25 emerged from the pits with a very big rear wing.
After the British team hinted it might not use an F-duct at all this weekend, the wing was indeed used on Friday morning in conjunction with the downforce-shedding innovation.
The implication is that McLaren achieves high straight-line speeds by activating the F-duct on the straights and stalling the wing, while in the corners the car gains a competitive advantage by producing higher-than-normal downforce.
Jenson Button topped the morning timesheets at the Italian circuit, while his teammate Lewis Hamilton was third quickest in the sister car.