David Beckmann secured his first ever GP3 Series pole position and Trident Racing's first of 2018 at Spa, with the top 17 separated by under a second.
Beckmann switched to Trident from Jenzer at the previous round at the Hungaroring, and the German's performance instantly improved.
He topped practice in Hungary and repeated that feat in Belgium, before following up his fastest time in qualifying.
With Pirelli's tyres capable of doing multiple laps, the order was extremely fluid, but Beckmann topped the times on the penultimate run.
As the four ART Grand Prix cars and Beckmann's three Trident team-mates all attempted to improve, only Piquet (Trident) could lower his time before Beckmann took shaved another tenth of a second from his best to assure his place at the top of the order.
Championship leader and ART driver Anthoine Hubert took second ahead of Piquet, while Hubert's team-mates Jake Hughes and Nikita Mazepin rounded out the top five.
Callum Ilott, Hubert's closest challenger in the points, could only manage sixth in his ART-run car, while Simo Laaksonen took his best qualifying result of the season, the Campos driver securing seventh ahead of a pair of Tridents.
Ryan Tveter had to settle for eighth when he failed to improve on his final run, while Giuliano Alesi's last time would have put him in the top five but it was disallowed for track limits.
Joey Mawson rounded out the top 10 for Arden. Another title contender, Leonardo Pulcini, had a difficult session and only managed 12th in the order.
On his debut with the team, MP Motorsport's Richard Verschoor took 15th, ahead of both of his team-mates Niko Kari (17th) and Devlin DeFrancesco (19th).
|2||Anthoine Hubert||ART Grand Prix||2m04.479s||0.144s|
|4||Jake Hughes||ART Grand Prix||2m04.530s||0.195s|
|5||Nikita Mazepin||ART Grand Prix||2m04.538s||0.203s|
|6||Callum Ilott||ART Grand Prix||2m04.549s||0.214s|
|7||Simo Laaksonen||Campos Racing||2m04.633s||0.298s|
|10||Joey Mawson||Arden International||2m04.712s||0.377s|
|11||Tatiana Calderon||Jenzer Motorsport||2m04.804s||0.469s|
|12||Leonardo Pulcini||Campos Racing||2m04.945s||0.610s|
|13||Juan Manuel Correa||Jenzer Motorsport||2m05.068s||0.733s|
|14||Gabriel Aubry||Arden International||2m05.135s||0.800s|
|15||Richard Verschoor||MP Motorsport||2m05.269s||0.934s|
|16||Julien Falchero||Arden International||2m05.278s||0.943s|
|17||Niko Kari||MP Motorsport||2m05.296s||0.961s|
|18||Diego Menchaca||Campos Racing||2m05.782s||1.447s|
|19||Devlin Defrancesco||MP Motorsport||2m05.974s||1.639s|
|20||Jannes Fittje||Jenzer Motorsport||2m06.036s||1.701s|