Red Bull's Max Verstappen led the field in Friday's second practice session, but the Dutchman held only a small 0.048s margin over an impressive Daniel Ricciardo.
However, the Renault driver's session ended early after a hydraulics issue ground his running. Lewis Hamilton clocked in third, 0.096s adrift from Verstappen while Alex Albon and Sergio Perez rounded off the top five.
FP1 pace setter Valtteri Bottas managed just sixth while Ferrari's drivers lingered once again at the bottom of the time sheet.
There was no rush to hit the track when the light at the end of the pitlane turned green for FP2, with an early light sprinkling of rain deterring drivers.
Finally, Alfa Romeo's Antonio Giovinazzi was the first driver to break the silence, the Italian having to play catch-up after a botched morning session in which he failed to put a time on the board.
Gradually, the traffic, albeit light, built up but Lando Norris was seen cruising around the track and back to his garage in a bizarre sounding McLaren, a problem that was eventually traced to a calibration issue.
Bottas' first effort was good for a 1m44.658s which wasn't that far off from his morning best. But Verstappen then shaved off a few tenths from the Finn's benchmark with a run on the mediums that delivered a 1m44.354s.
Verstappen, Hamilton and Bottas all switched to the soft rubber and headed back out, with times predictably falling.
Bottas first descended to a 1m44.162s that was blitzed in short order by his Mercedes teammate with a 1m43.840s.
Albon then slotted into second behind Hamilton, followed by Perez, with both drivers relying on the soft compound.
But all-out flyers from Verstappen and Ricciardo placed the former Red Bull team mates at the top of the timing screen, with max setting the ne target at 1m43.744s.
Meanwhile, there were no signs of improvement down at Ferrari, with both Leclerc and Vettel engulfed in the lower tier of the field despite undertaking runs on the soft tyre.
In other Ferrari-related news, Haas' Kevin Magnussen and Romain Grosjean finally sprang into action after both drivers suffered engine issues in FP1.
Traffic increased as the session entered its final 30 minutes, with teams reverting to long runs to prepare for race day.
But Ricciardo's parked Renault on the Kemmel straight brought out a Virtual Safety Car. Oddly, there was no visible or audible tell-tale sign to justify the Aussie's halt but the team later traced the problem to a hydraulic issue.
With less than 13 minutes to go, the red flag was deployed for "debris on the track after Turn 1", which turned out to be a pair of detached advertising boards located on the armco on the run down to Eau Rouge.
The session resumed after a short respite but positions remained unchanged among the front-runners, with Verstappen topping the time sheet from Ricciardo, Hamilton, Albon and Perez.
Further back, Bottas edged Norris, Ocon, Sainz while Gasly rounded off the top ten.
In the second half of the field, Ferrari's bad day was clear for all to see with Leclerc and Vettel concluding FP2 respectively P15 and P16, with Williams' George Russell slotted between the red cars.
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