Yamamoto credits Button advice for Fuji DTM/Super GT Honda form

Button and Yamamoto have shared a Kunimitsu Honda NSX in the Super GT Championship for the last two years, winning the title at their first attempt in 2018 following Button's F1 retirement.

With the joint Super GT and DTM races however, only one driver competes. Button undertook the Hockenheim running alone and impressed as Super GT's best-placed finisher, notably qualifying his NSX sixth before taking ninth in the opening race.

With Button competing in the Baja 1000 during the Fuji weekend, Yamamoto took over at Fuji last weekend and impressed with third and fourth-place finishes.

"Jenson went to Hockenheim and he drove there and he was disappointed with their result and the car," Yamamoto explained following the first race.

"But he gave me a good set-up, and information, which is great news.

"It's great information so I want to say thank you very much JB!"

Asked by Autosport to explain where Button's advice had helped most, Yamamoto said: "He told me that the Hankook tyres are really low grip, so take care!

"It's really difficult to manage the temperature and the working range is so close and narrow. That's difficult to manage.

"I focused on the management of the temperatures this weekend and until yesterday it was tough. But from qualifying, it was working well."

Like all Super GT runners, Yamamoto took part in four test sessions on Thursday and Friday designed to help the drivers and teams acclimatise to the DTM's spec Hankook tyre.

Several within the DTM paddock expressed surprise at how quickly the Super GT field adapted to the Hankook tyre at Fuji - especially the wet compound that has proven difficult in 2019 - and it helped Super GT largely hold an edge over the DTM at Fuji.

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While at Hockenheim the three Super GT teams conducted radical set-up work not seen in Super GT due to its reliance on specialised tyres, Yamamoto said a switch to a conventional set-up help unlock the Honda's potential.

"At the beginning of the session, the first test day, I just went from the Hockenheim [set-up]," he said.

"But on the first ride, it was not good.

"We did changes to the set-up and went to the usual Japanese car set-up. After the first lap, it felt better than the first day of running."

Button and Yamamoto struggled to recreate their 2018 Super GT form this season - which was Button's last as he has now left the series - blaming a botched pre-season aerodynamic upgrade which was dropped entering the season. They finished eighth without a win.