Button, who finished on the podium in only his second Super GT appearance earlier this month, lapped the Suzuka Circuit in 1m45.787s in the afternoon session.

That time put #100 Team Kunimitsu Honda just over a tenth clear of the #38 Zent/Cerumo Lexus of defending Super Formula champion Hiroaki Ishiura.

2017 All Japan F3 champion Mitsunori Takaboshi made it three different manufacturers in the the top three by setting a time of 1m46.177s in the #24 Kondo Nissan, 0.390s down on Button’s chart-topping lap time.

Defending GT500 champion Ryo Hirakawa was another 0.365s behind in the #1 TOM’S Lexus, while the top five was completed by the #17 Real Racing Honda of Takashi Kogure.

Fresh from his Blancpain GT Asia debut, two-time Super GT champion and #23 NISMO driver Tsugio Matsuda set the sixth-fastest time of the day, while Daisuke Nakajima was seventh in the #16 Mugen Honda.

ARTA’s Takuya Izawa and Team LeMans driver James Rossiter were eighth and ninth respectively, separated by just 0.030s.

Rossiter, who has made a full-time switch to Super Formula this year, was preparing for his Suzuka 300km appearance, where he will replace Formula E star Felix Rosenqvist. He will also take part in the next round of Super GT championship at Fuji in place of Kazuki Nakajima at TOM’S.

Behind Rossiter, the top 10 was rounded off by the #12 Impul Nissan of Daiki Sasaki.

Testing results (top 10):