Honda has confirmed that Max Verstappen will start the Italian Grand Prix from the back of the grid, with Red Bull opting to take an upgraded engine on the Dutchman's car at Monza.
Pierre Gasly will also join his former team-mate at the back of the grid, as Honda deliver more upgrades following Alexander Albon and Daniil Kvyat taking the update in Spa last weekend.
Verstappen is in need of a response after crashing out on lap one in Belgium, having sustained damage in a collision with Kimi Raikkonen at the first corner.
It has previously been suggested that Honda's fourth upgrade of the year will represent a big step and Albon was able to fight to fifth place in Spa from 17th on the grid.
With Red Bull traditionally struggling at the 'Temple of Speed' in recent years, Verstappen's best result there in recent years is last year's penalty-affected fifth-placed finish, but Honda issued a confident preview for the race.
Honda technical director Toyoharu Tanabe said: "We now go from one classic track to another, from Spa to Monza for the Italian Grand Prix, which is the last race in Europe this year.
"It is one of the highlights of the season and also the home race for one of our teams, Scuderia Toro Rosso.
"From a PU point of view, the main development is that we plan to run the Spec 4 PU with all four drivers for the first time, after just Albon and Kvyat ran it in Belgium.
"For their first race with Spec 4, Gasly and Verstappen will therefore take grid penalties and start from the back of grid, but we believe they can still race strongly on Sunday."