The two Toyotas were separated by just over a tenth of a second at the top of the times at the end of the first session of the official Le Mans 24 Hours test.
Sebastien Buemi ended up quickest aboard the #8 Toyota TS050 HYBRID thanks to a 3m21.875s lap set right at the end of the four-hour morning session.
That jumped him ahead of the sister car in which Jose Maria Lopez had led the way for much of the session with a 3m22.027s tour.
Those times compare with the 3m21.468 lap with which Fernando Alonso topped the times after the morning of the test day last year when the Toyotas were running 10kg lighter.
Gustavo Menezes vaulted into the best of the rest position behind the Toyotas, two seconds down, right at the end aboard the #3 Rebellion-Gibson R-13.
His 3m23.926s put him ahead of the two SMP Racing BR Engineering BR1s that ended up fourth and fifth.
Vitaly Petrov was fourth fastest on a 3m24.389s aboard the best of the AER-engined BR1s, which was just over a tenth quicker than Stephane Sarrazin's 3m24.529s in the fifth-placed sister car.
The best of the United Autosports team's pair of Ligier-Gibson JSP217s went quickest in LMP2.
Filipe Albuquerque, who had flown in overnight after competing in Saturday's IMSA SportsCar Championship round in Detroit, set a 3m32.242s lap time as the clock clicked down to just shade the DragonSpeed ORECA-Gibson 07.
Pastor Maldonado was just two thousands behind for DragonSpeed on 3m32.244s, which in turn was only five hundredths up on Jonathan Hirschi in the Graff team's ORECA.
The Racing Team Nederland Dallara and IDEC Sport's ORECA took fourth and fifth positions to make it a 1-2-3-4-5 in LMP2 for cars running Michelin tyres.
The top Dunlop-shop P2 car was the TDS Racing ORECA in which Loic Duval set a 3m33.127s.
Chevrolet ended up quickest in GTE Pro won a 3m55.704s set by Antonio Garcia right at the end of the four hours.
That jumped the #63 Corvette C7.R ahead of the best of the Ganassi Ford GTs in which Billy Johnson had earlier posted a 3m55.728s.
Porsche driver Gianmaria Bruni and Ferrari's Daniel Serra made it four marques within just over two tenths of a second at the top of the class times.
Francesco Castellacci was fastest in GTE Am aboard the Spirit of Race Ferrari.