Stoffel Vandoorne will serve a 35-place grid penalty at the Belgian GP due to a scheduled power unit change, McLaren have confirmed.
Both Vandoorne and team-mate Fernando Alonso are running upgraded Honda engines at Spa, but only the rookie has been hit with a hefty grid drop and will almost certainly start at the back this weekend.
"Unfortunately Stoffel will receive a grid penalty at his home grand prix, but it is important for us to introduce updates as soon as they are ready," said Honda's F1 chief Yusuke Hasegawa-San.
"It is positive that we have been able to introduce this next step forward so quickly, and we will continue to introduce updates throughout the remainder of the season."
Honda claim Vandoorne's 3.6-spec power unit should give him extra performance and reliability, but McLaren and their drivers are still paying for a first half of the 2017 season that was riddled by car and engine failures.
"The penalties were inevitable because of the issues we had earlier this season," Vandoorne said in the drivers' press conference.
"Every part we bring to the car now is giving us grid penalties. It's a shame to start the weekend like that, but with the weather here there may be a lot of opportunities."
Vandoorne is looking to build on scoring his first F1 points at the last race in Hungary, while he has also been assured of his 2018 drive with McLaren ahead of the Spa weekend.
Alonso, meanwhile, who took a 30-place grid drop at the British GP last month, is set for a penalty-free weekend with a 3.5-spec engine. However, the Spaniard has warned that the iconic Belgian track may not suit the MCL32's package.