Driving Porsche Penske Motorsport’s #6 963 LMDh, Estre set a blistering time of 1m39.990s at the beginning of the 90-minute session that was cut short by a stoppage for the new Lamborghini SC63 LMDh.
Estre was the only driver to get below team-mate Frederic Makoweicki’s benchmark of 1m40.404s, which was set in relatively hotter conditions at the Losail International Circuit in the two-day Prologue, with his nearest challenger Jean-Eric Vergne only managing a best time of 1m40.772s in the #93 Peugeot.
Vergne was closely followed by Jenson Button in the #38 Jota customer Porsche, with the 2009 Formula 1 world champion also completing an early qualifying simulation to end up just 0.010s adrift in third.
The Chip Ganassi-run Cadillac ended up fourth in the order courtesy of Alex Lynn’s effort of 1m40.986s, with Matt Campbell rounding out the top five in the #6 Porsche.
IndyCar convert Callum Ilott briefly held the top spot on the timesheets, but his early flyer of 1m41.328s in the #12 Jota Porsche left him sixth in the final order, 1.3s off the pace of the factory 963 of Estre.
Antonio Giovinazzi propelled the #51 Ferrari 499P to seventh shortly after the first red flag, which was deployed 26 minutes into the session when Isotta Fraschini’s Tipo 6 LMH got beached in the gravel at Turn 6 with Jean-Karl Vernay at the wheel.
A second red flag would follow with just 10 minutes remaining in the session after Mirko Bortolotti crawled to a halt in the Lamborghini SC63 at Turn 7, likely due to a mechanical issue.
A decision was subsequently taken not to restart second practice.
That left the #7 Toyota GR010 Hybrid a distant eighth in the order, with new recruit Nyck de Vries ending up more than 1.5s off the pace on what is turning out to be a challenging weekend for the Japanese manufacturer.
The #7 Toyota was closely followed by the second Peugeot, whose best lap was set by Stoffel Vandoorne, while the AF Corse customer team completed the top 10 with Yifei Ye driving the #83 Ferrari.
Ye marginally shaded the #50 factory Ferrari of Antonio Fuoco and Lamborghini’s sole LMDh contender, which was still the fastest car among all the new manufacturers joining the top class this year.
The top Alpine A424 was classified only 14th, while Sheldon van der Linde finished another position behind in 15th in the #20 BMW Hybrid V8, which didn’t venture out on track until halfway through the session.
In LMGT3, Ferrari secured a one-two finish in class courtesy of the AF Corse team.
Simon Mann improved to a 1m55.190s in the #55 Ferrari 296 GT3 to overhaul the sister car that had held the top spot from the beginning of the session with Davide Rigon at the wheel.
Rigon’s team-mate Francesco Castellacci later found more time in the #54 entry to end up a quarter of a second off the pace, as Sean Gelael finished third in the #31 WRT BMW M4 GT3.
Erwan Bastard put the #777 D’station Aston Martin Vantage GT3 fourth in the order, ahead of the #5 United Autosports McLaren 720S GT3 of Marino Sato.
