Marc Lieb topped the times for Porsche during a rain-affected first practice session for the Spa round of the World Endurance Championship.
The German driver set a best time of 2m16.617s aboard the #18 Porsche 919 Hybrid in the first half of the session, which was stopped for nearly half an hour following an incident involving the Kazuki Nakajima's Toyota and the Audi of Oliver Jarvis.
The Japanese driver has been taken to hospital for checks after complaining of back pain after the clash.
Lieb's time, set on a wet but drying track, put him half a second clear of Anthony Davidson's 2m17.117s in the #1 Toyota TS040 HYBRID he shares with Nakajima and Sebastien Buemi.
Third fastest, a further two tenths back, was Brendon Hartley in the second of the three 919 Hybrids, while Nico Hulkenberg was fourth on his sportscar debut with Porsche.
Rene Rast was the fastest Audi aboard the solo high-downforce R18 e-tron quattro entered for Saturday's race.
A time of 2m20.337s was good enough for fifth and put the German driver 1.2 seconds clear of sixth-placed Loic Duval in the first of the Le Mans-spec low-downforce Audis.
All the leading times were set early in the session before light rain intensified. It was still raining hard when the session restarted for 27 minutes after the Nakajima/Jarvis incident at the end of the Kemmel Straight.
The Srakka Dome-Nissan S103, the only LMP2 runner on Michelin tyres, was quickest in class with Jonny Kane driving.
His time of 2m23.672s put him just over a second clear of the Dunlop-shod Jota Sport Gibson-Nissan 015S in the hands of Harry Tincknell.
Porsche led the way in GTE Pro: Kevin Estre, on loan from McLaren for this race, topped the times on a 2m26.055s, which put him six tenths up on Manthey team-mate Frederic Makowiecki.
It was also quickest in GTE Am with the Proton Porsche 911 RSR driven by Klaus Bachler.
PRACTICE ONE RESULTS:
|1||LMP1||R.Dumas, N.Jani, M.Lieb||Porsche Team||Porsche||2m16.616s||-|
|2||LMP1||A.Davidson, S.Buemi, K.Nakajima||Toyota Racing||Toyota||2m17.117s||0.501s|
|3||LMP1||T.Bernhard, M.Webber, B.Hartley||Porsche Team||Porsche||2m17.309s||0.693s|
|4||LMP1||N.Hulkenberg, E.Bamber, N.Tandy||Porsche Team||Porsche||2m18.157s||1.541s|
|5||LMP1||F.Albuquerque, M.Bonanomi, R.Rast||Audi Sport Team Joest||Audi||2m20.337s||3.721s|
|6||LMP1||L.di Grassi, L.Duval, O.Jarvis||Audi Sport Team Joest||Audi||2m21.552s||4.936s|
|7||LMP1||A.Wurz, S.Sarrazin, M.Conway||Toyota Racing||Toyota||2m22.232s||5.616s|
|8||LMP1||M.Fassler, A.Lotterer, B.Treluyer||Audi Sport Team Joest||Audi||2m23.857s||7.241s|
|9||LMP2||N.Leventis, D.Watts, J.Kane||Strakka Racing||Dome/Nissan||2m32.672s||16.056s|
|10||LMP2||S.Dolan, M.Evans, H.Tincknell||JOTA Sport||Gibson/Nissan||2m33.887s||17.271s|
|11||LMP2||G.Yacaman, P.Derani, R.Gonzalez||G-Drive Racing||Ligier/Nissan||2m33.946s||17.330s|
|12||LMP2||R.Rusinov, J.Canal, S.Bird||G-Drive Racing||Ligier/Nissan||2m35.204s||18.588s|
|13||GTE Pro||S.Muller, K.Estre||Porsche Team Manthey||Porsche||2m36.065s||19.449s|
|14||LMP2||N.Panciatici, P-L.Chatin, V.Capillaire||Signatech Alpine||Alpine/Nissan||2m36.452s||19.836s|
|15||LMP2||P.Ragues, O.Webb, Z.Amberg||Team SARD Morand||Morgan/SARD||2m36.506s||19.890s|
|16||GTE Pro||F.Makowiecki, R.Lietz||Porsche Team Manthey||Porsche||2m36.666s||20.050s|
|17||GTE Pro||G.Bruni, T.Vilander||AF Corse||Ferrari||2m36.698s||20.082s|
|18||GTE Pro||A.MacDowall, F.Rees, R.Stanaway||Aston Martin Racing V8||Aston Martin||2m36.709s||20.093s|
|19||GTE Pro||D.Turner, S.Mucke, R.Bell||Aston Martin Racing||Aston Martin||2m37.148s||20.532s|
|20||LMP2||M.Howson, R.Bradley, N.Lapierre||KCMG||ORECA/Nissan||2m37.303s||20.687s|
|21||GTE Pro||D.Rigon, J.Calado||AF Corse||Ferrari||2m37.563s||20.947s|
|22||GTE Pro||C.Nygaard, M.Sorensen, J.Adam||Aston Martin Racing||Aston Martin||2m38.568s||21.952s|
|23||GTE Am||C.Ried, K.Al Qubaisi, K.Bachler||Abu Dhabi-Proton Racing||Porsche||2m39.885s||23.269s|
|24||GTE Am||P.D.Lana, P.Lamy, M.Lauda||Aston Martin Racing||Aston Martin||2m40.459s||23.843s|
|25||GTE Am||D.Cameron, M.Griffin, A.Mortimer||AF Corse||Ferrari||2m40.559s||23.943s|
|26||GTE Am||V.Shaytar, A.Bertolini, A.Basov||SMP Racing||Ferrari||2m41.033s||24.417s|
|27||LMP1||S.Trummer, V.Liuzzi, C.Klien||Team ByKolles||CLM/AER||2m41.506s||24.890s|
|28||GTE Am||F.Perrodo, E.Collard, R.Aguas||AF Corse||Ferrari||2m41.526s||24.910s|
|29||GTE Am||G.Roda, P.Ruberti, K.Poulsen||Larbre Competition||Chevrolet||2m42.824s||26.208s|
|30||GTE Am||F.Castellacci, R.Goethe, S.Hall||Aston Martin Racing||Aston Martin||2m43.369s||26.753s|
|31||GTE Am||P.Dempsey, P.Long, M.Seefried||Dempsey-Proton Racing||Porsche||2m43.509s||26.893s|
|32||LMP2||E.Brown, J.van Overbeek, J.Fogarty||Extreme Speed Motorsports||Ligier/HPD||2m44.395s||27.779s|
|33||LMP2||S.Sharp, R.Dalziel, D.H.Hansson||Extreme Speed Motorsports||Ligier/HPD||2m44.440s||27.824s|
|34||LMP2||J.Nicolet, J-M.Merlin, E.Maris||Oak Racing||Ligier/Nissan||2m45.768s||29.152s|
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