Monza - Red Bull's Max Verstappen and Toro Rosso's Pierre Gasly will start Sunday's Italian Grand Prix at the back of the grid due to power unit changes, engine partners Honda said on Wednesday.
Both will use Honda's latest 'Spec 4' unit, taking them beyond their engine allocation for the season.
"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," said Honda's F1 technical director Toyoharu Tanabe in a statement.
By taking penalties at Monza, the fastest track on the calendar, Red Bull aim to give Verstappen a better chance in Singapore later in the month where grid position is more important and overtaking is difficult.
The Japanese Grand Prix, Honda's home race, is also coming up in October.