Last year's winners Ferrari faced the prospect of an embarrassing qualifying performance on Saturday after a disappointing final practice for the Belgian Grand Prix.
Charles Leclerc, who claimed his maiden F1 victory last year, was 17th and four-time champion Sebastian Vettel 20th and last in the session, the two Ferrari men struggling even to match the Italian outfit’s customer teams.
The two Haas drivers, powered by Ferrari engines, Kevin Magnussen and Romain Grosjean, were 14th and 15th ahead of Ferrari-powered Alfa Romeo’s Kimi Raikkonen, 16th.
Team boss Mattia Binotto had warned on Friday that Ferrari faced a host of issues as they battled to find performance at the long, demanding and high-speed Spa-Francorchamps circuit.
The team has struggled this year with a power deficit to their rivals, but Binotto said it was not only this deficiency that hampered their speed, but also a struggle to warm up their tyres and find balance.
"We struggle to make the tyres work," said Binotto. "We are lacking grip, both in braking and acceleration. There is no overall performance to the car. So certainly the drivers are complaining about grip, overall grip.
“I think it's the same situation on both cars so it's not driver related. It's really the way we set up the car in order to find the right window on the tyres."
He added that it was a difficult challenge for the team to solve as they sought a well-balanced aerodynamic set-up for a track that always demands a precise level of down-force.
Three-quarters of the lap is driven at top speed, requiring minimum down-force, while the other quarter requires more down-force to cope with slower sections with corners.
The last time a Ferrari driver qualified at the back of the grid was in 2009 with Luca Badoer.