Matthieu Vaxiviere set the fastest time in Formula Renault 3.5 practice at Spa on Friday, leading the way in the second of two sessions
The Lotus F1 junior driver recorded a lap of 1m59.620s in the afternoon's 50 minutes, to edge out morning pacesetter Tio Ellinas by 0.210 seconds.
Strakka racer Ellinas moved to the head of the timing screens in the final two minutes of FP1 thanks to a time of 2m00.307s.
Although the circuit was declared wet prior to the opening FR3.5 session, rain had ceased and slicks were the tyre of choice.
But only 10 minutes after the green, Monaco winner Jazeman Jaafar was caught out by a damp patch and left the track on the exit of Rivage, bringing out the red flags.
The second session was red-flagged after nine minutes when Tech 1 Racing's Roy Nissany stopped at Raidillion.
Monaco podium finisher Tom Dillmann had been fastest at the time of the first stoppage in FP2 on a time of 2m02.187, 0.031s ahead of Arden's Nicholas Latifi, but the order changed comprehensively in the final few minutes when drivers mounted new tyres.
The lead changed hands between Latifi, Ellinas and Vaxiviere, with Oliver Rowland - who experimented with low downforce in FP1 - also threatening.
Drivers were robbed of a last opportunity to demote Vaxiviere when yellow flags appeared on the exit of Rivage after a car stopped by the side of the road.
Following his blistering drive through the field in Monaco, Rowland ended the afternoon in third, ahead of Latifi and Dutch drivers Beitske Visser and Meindert van Buuren.
Brazilian Pietro Fantin, who has enjoyed a consistent start to the season, was second quickest in FP1, just 0.050s ahead of Vaxiviere.
Fantin caused one of two stoppages in the afternoon when he suffered an incident at the right-hand Courbe Paul Frere, leading into Blanchimont.
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