Buemi jumped to the head of the timesheets after a 12-minute red flag midway through session aboard the #8 Toyota GR010 HYBRID Le Mans Hypercar with a 2m02.982s that gave him a margin of more than a second and a half over Ferrari driver Antonio Fuoco.
Fuoco also set his time in the #50 Ferrari 499P LMH, a 2m04.632s, straight after the red to sneak ahead of the second Toyota of Jose Maria Lopez.
Lopez had been quickest up to the stoppage, caused by Luis Perez Companc going off at Les Combes in the Richard Mille-sponsored AF Corse Ferrari 488 GTE Evo.
The Toyota driver’s 2m04.642s set at the start of the session left him just one hundreth of a second behind the Ferrari.
Buemi’s time represented an improvement of nearly four seconds for Toyota over the corresponding session at Spa this time last year.
The 90-minute session was red flagged for a second time and did not restart after an incident involving the Vanwall LMH and the D’Station GTE Am Aston.
Ferrari took fourth position courtesy of a 2m04.716s from Alessandro Pier Guidi in the #51 entry run by the AF Corse factory team.
Laurens Vanthoor was only a tenth behind as he took fifth position for Porsche in the best of the Penske-run 963 LMDhs with a 2m04.870s.
Cadillac ended up sixth with the best of the Ganassi-run V-Series.R LMDhs in which Alex Lynn posted a 2m05.347s.
Michael Christensen took seventh in the second Porsche on 2m05.807s, while Gustavo Menezes ended up eighth in the best of the Peugeot 9X8 LMHs with a 2m06.259s.
Sebastien Bourdais was ninth in the additional Cadillac Racing entry from Ganassi and Paul di Resta rounded out the top 10 in Hypercar behind three LMP2 cars aboard the second Peugeot.
Glickenhaus and Vanwall were 11th and 12th, while the British Jota team’s brand new Porsche 963 brought up the rear of the class in the hands of Will Stevens on its debut on track.
The Hertz-sponsored car had completed only a one-hour shakedown prior to Spa in wet conditions on the Porsche’s Weissach test track in the hands of Matt Campbell last week.
Filipe Albuquerque was quickest for United Autosports in LMP2 with a a 2m07.471s in its #22 ORECA-Gibson 07, which gave him a margin of less than a tenth over Pietro Fittipaldi in Jota’s solo P2 entry.
The Brazilian’s 2m07.514s was more than two tenths up on Tom Blomqvist in the #23 United car.
Daniel Serra led the way in GTE Am for the Kessel Ferrari team.
His 2m16.177s was six tenths ahead of Ulysse de Pauw’s 2m16.717s in the fastest of the AF Corse entries in class.
Second free practice begins at 16:20 local time in Spa.
WEC Spa - FP1 results:
| Cla | Nº | Driver | Car / Engine | Time | Gap |
|---|---|---|---|---|---|
| 1 | 8 | Sébastien Buemi Brendon Hartley Ryo Hirakawa |
Toyota | 2'02.982 | |
| 2 | 50 | Antonio Fuoco Miguel Molina Nicklas Nielsen |
Ferrari | 2'04.632 | 1.650 |
| 3 | 7 | Mike Conway Kamui Kobayashi José María López |
Toyota | 2'04.642 | 1.660 |
| 4 | 51 | A.P.Guidi James Calado A.Giovinazzi |
Ferrari | 2'04.716 | 1.734 |
| 5 | 6 | Kévin Estre André Lotterer Laurens Vanthoor |
Porsche | 2'04.870 | 1.888 |
| 6 | 2 | Earl Bamber Alex Lynn R.Westbrook |
Cadillac | 2'05.347 | 2.365 |
| 7 | 5 | Dane Cameron M.Christensen F.Makowiecki |
Porsche | 2'05.807 | 2.825 |
| 8 | 94 | Loïc Duval Gustavo Menezes Nico Müller |
Peugeot | 2'06.259 | 3.277 |
| 9 | 3 | S.Bourdais R.van der Zande Jack Aitken |
Cadillac | 2'07.382 | 4.400 |
| 10 | 22 | Freddie Lubin Phil Hanson F.Albuquerque |
ORECA/Gibson | 2'07.471 | 4.489 |
| 11 | 28 | David H.Hansson P.Fittipaldi Oliver Rasmussen |
ORECA/Gibson | 2'07.514 | 4.532 |
| 12 | 23 | Josh Pierson Tom Blomqvist Oliver Jarvis |
ORECA/Gibson | 2'07.753 | 4.771 |
| 13 | 93 | Paul Di Resta Mikkel Jensen Jean-Éric Vergne |
Peugeot | 2'07.769 | 4.787 |
| 14 | 34 | J.Smiechowski Fabio Scherer Albert Costa |
ORECA/Gibson | 2'07.799 | 4.817 |
| 15 | 63 | Doriane Pin Mirko Bortolotti Daniil Kvyat |
ORECA/Gibson | 2'07.809 | 4.827 |
| 16 | 708 | Romain Dumas Olivier Pla Franck Mailleux |
Glickenhaus/Pipo | 2'07.948 | 4.966 |
| 17 | 41 | Rui Andrade Robert Kubica Louis Delétraz |
ORECA/Gibson | 2'07.996 | 5.014 |
| 18 | 9 | Filip Ugran Bent Viscaal A.Caldarelli |
ORECA/Gibson | 2'08.180 | 5.198 |
| 19 | 31 | Sean Gelael F.Habsburg Robin Frijns |
ORECA/Gibson | 2'08.200 | 5.218 |
| 20 | 36 | M.Vaxivière Julien Canal Charles Milesi |
ORECA/Gibson | 2'08.781 | 5.799 |
| 21 | 4 | Tom Dillmann E.Guerrieri J.Villeneuve |
Vanwall/Gibson | 2'08.906 | 5.924 |
| 22 | 38 | A.F.da Costa Will Stevens Yifei Ye |
Porsche | 2'09.048 | 6.066 |
| 23 | 35 | André Negrão Memo Rojas Olli Caldwell |
ORECA/Gibson | 2'09.439 | 6.457 |
| 24 | 10 | Ryan Cullen Matthias Kaiser Gabriel Aubry |
ORECA/Gibson | 2'10.152 | 7.170 |
| 25 | 57 | Takeshi Kimura Scott Huffaker Daniel Serra |
Ferrari | 2'16.177 | 13.195 |
| 26 | 21 | Diego Alessi Simon Mann Ulysse De Pauw |
Ferrari | 2'16.717 | 13.735 |
| 27 | 25 | Ahmad Al Harthy Michael Dinan Charlie Eastwood |
Aston Martin | 2'17.163 | 14.181 |
| 28 | 56 | PJ Hyett Gunnar Jeannette Matteo Cairoli |
Porsche | 2'17.440 | 14.458 |
| 29 | 83 | L.P.-Companc Lilou Wadoux Alessio Rovera |
Ferrari | 2'17.555 | 14.573 |
| 30 | 777 | Satoshi Hoshino Casper Stevenson Tomonobu Fujii |
Aston Martin | 2'17.637 | 14.655 |
| 31 | 60 | C.Schiavoni Matteo Cressoni A.Picariello |
Porsche | 2'17.770 | 14.788 |
| 32 | 98 | Ian James D.Mancinelli Alex Riberas |
Aston Martin | 2'17.945 | 14.963 |
| 33 | 33 | Ben Keating Nico Varrone Nicky Catsburg |
Chevrolet | 2'17.978 | 14.996 |
| 34 | 85 | Sarah Bovy Michelle Gatting Rahel Frey |
Porsche | 2'18.053 | 15.071 |
| 35 | 86 | Mike Wainwright Riccardo Pera Ben Barker |
Porsche | 2'18.213 | 15.231 |
| 36 | 88 | Ryan Hardwick Z.Robichon Harry Tincknell |
Porsche | 2'18.401 | 15.419 |
| 37 | 77 | Christian Ried M.O.Pedersen Julien Andlauer |
Porsche | 2'18.546 | 15.564 |
| 38 | 54 | Thomas Flohr F.Castellacci Davide Rigon |
Ferrari | 2'18.744 | 15.762 |
