Global Motorsport Media
The McLarens, led by Lewis Hamilton, were quickest in the first dry and sunny practice session ahead of the Italian grand prix, before championship leader Sebastian Vettel edged ahead in the afternoon on Friday.
"I think we can challenge the Red Bulls this weekend, but it's going to be a hard race," said Briton Hamilton.
Vettel admitted that the high speed Autodromo is not a layout that "traditionally suits" his Red Bull car "but we were happy with the car today".
"McLaren look very quick in particular and (are) the ones to beat this weekend," the German added.
His teammate Mark Webber confirmed that Red Bull "readjusted a few things" in the wake of Pirelli's tyre camber guidelines.