Max Verstappen is set to take "a bunch of penalties" at Monza after his Renault engine failed again and forced him to retire from Sunday’s Belgian Grand Prix, his Red Bull boss Christian Horner predicted.
Horner complained that Renault was giving his team a "below par" service – for which the French constructor’s representative Alain Prost apologised personally to Verstappen – despite seeing his teammate Daniel Ricciardo claim third behind race winner Lewis Hamilton.
The team chief added that Verstappen’s post-race outburst of frustration with the team, and thinly-veiled threat that he was considering his future, was to be expected.
"He's just enormously frustrated, as you can imagine," said Horner. "Once again, he's in a great position and through no fault of his own he's had another engine issue.
"Sometimes words escape you... obviously he's had Alain Prost come and apologise, Renault are going to apologise, but it doesn't change the situation unfortunately.
"I think that Renault are quite aware that their reliability and product isn't where it should be and that's their business to sort that out.
"We're a paying customer and it's obviously below par -- the service that we're seeing at this point in time, because of the reliability issues. We're staring down the barrel at a bunch of penalties at Monza."
Verstappen was fifth and had completed just eight laps in front of an 80,000-strong Dutch army in a record crowd at the spectacular Spa-Francorchamps – more than 265,000 packed in during the weekend – before he lost power and parked his car.
It was his sixth retirement in 12 races.
"I can understand his frustration, but the majority of them have been beyond our control," explained Horner.
"He's now staring down the barrel of a bunch of penalties in Monza so it is really frustrating for him.
"He's just been desperately unlucky. The issues haven't been car-related, it's been engine-related.
"We don't know what happens behind the scenes, but Renault has always supplied equal equipment to both drivers in all the history we have had. It's bad luck the failures on a Sunday seem to be happening on his side of the garage.
"Daniel has had as many failures, but they have tended to be on Fridays and Saturdays rather than Sunday afternoons."