Fernando Alonso held a narrow advantage for Toyota at the top of the Le Mans test times when the opening session was stopped early as a result of a major accident.
The #8 Toyota TS050 HYBRID held an advantage of just under four tenths clear when the four-hour morning session was red-flagged with approximately 50 minutes to go after Marco Sorensen crashed his Aston Martin.
Alonso's time of 3m21.468s compared with second placed Thomas Laurent's 3m21.828s in the #3 Rebellion-Gibson R-13.
The best of the non-hybrid privateer LMP1 entries ended up three tenths ahead of the second Toyota, which finished with a 3m22.187s in the hands of Mike Conway.
The official test, which is taking two weeks ahead of the Le Mans 24 Hours round of the World Endurance Championship on June 16/17, was halted as a result of extensive barrier damage after Sorensen's accident in the #95 Aston Martin Vantage GTE.
The Dane went off following contact with Harrison Newey in the SMP Racing Dallara-Gibson P217 on the fast run between Mulsanne and Indianapolis corners.
Sorensen was transported to the circuit medical centre for precautionary checks and subsequently released.
The second of the two Rebellion privateer P1s took fourth in the times with a 3m23.595s from Bruno Senna.
The two SMP Racing BR Engineering BR1s and the ByKolles ENSO CLM-Nissan P1/01 were the only other P1s to set representative times over the opening hours of testing.
G-Drive Racing reserve driver Alexandre Imperatori led the way in LMP2 in the team's lead ORECA-Gibson 07 run in conjunction with the TDS Racing squad.
The Swiss posted a time of 3m30.176s, which put him seven tenths up on Pau-Loup Chatin in the IDEC Sport ORECA.
The four Chip Ganassi Racing Ford GTs blocked out the top positions in GTE Pro.
The British-entered #67 entry was quickest on a 3m55.008s from Any Priaulx, which put it nine tenths up on the sister #66 WEC entry with Stefan Mucke at the wheel.
Best of the rest was the #91 Porsche 911 RSR, running in a retro livery inspired by the Rothmans Group C cars of the 1980s, with a 3m54.713s from Gianmaria Bruni.
Keita Sawa was quickest in GTE Am in the Clearwater Ferrari 488 GTE on a 3m58.569s.