Tsuboi's quickest time of the day came late on in the two-hour morning session, as he posted a 1m18.150s to beat the ARTA Honda NSX-GT of Tomoki Nojiri by a scant 0.034 seconds.
Honda's three Bridgestone-shod cars, now using the Type S bodywork revealed last month, locked out positions two through four, with Real Racing newcomer Nobuharu Matsushita setting the pace in the afternoon session with a 1m18.215s set during the 10 minutes of GT500-only running.
