Top speeds at Spa are registered on the track's Kemmel Straight, which runs from the exit of Eau Rouge to the Les Combes corner.
Thanks to their low-drag aero configuration, and the grunt of their Mercedes engine, Force India's Esteban Ocon and Sergio Perez whizzed through the speedtrap at 318.4 and 317.6 km/h respectively, just beating Valtteri Bottas by a whisker.
Looking down the order, McLaren's Fernando Alonso clocked in tenth at 310.5 km/h, a top speed deficit which once again underlines the efficiency of his MCl32 chassis.
Stoffel Vandoorne, who was using Honda's new spec-3.6 engine, was strangely relegated down to P17 with a top velocity of just 303.5 km/h.
Sauber's underpowered pair of Marcus Ericsson and Pascal Wehrlein were the usual laggards.
Gallery: The beautiful wives and girlfriends of F1
Keep up to date with all the F1 news via Facebook and Twitter
Helmut Marko believes that Red Bull and Max Verstappen are unlikely to challenge for victory…
Automotive giant General Motors is reportedly back in the game as a potential entrant in…
The opening day of running at the Las Vegas GP was a smooth but chilly…
Williams is continuing to fight uphill battles this weekend in Las Vegas as a knock-on…
It was a solid start to the Las Vegas weekend for Ferrari with Carlos Sainz…
Lando Norris didn’t hold back in his assessment of McLaren’s performance on the opening day…