Sakaguchi, who shares the Yokohama-shod #19 Toyota GR Supra with Yuji Kunimoto, recorded a best time of 1m18.074s around half an hour into the two-hour morning session to top the times by exactly a tenth of a second.
While that was a considerable improvement from the team's best time on the opening day of testing on Saturday, it was still 0.247s shy of the benchmark established by ARTA Honda driver Nirei Fukuzumi.
