Reigning Super GT champion Jenson Button says he was concerned he might not even score points at Fuji after qualifying only 12th for the season's second-longest race.
Button and Kunimitsu Honda team-mate Naoki Yamamoto failed to progress to Q2 for the first time since last August's Fuji 500-mile event, and 12th place marked their worst qualifying result since they first teamed up at the start of 2018 season.
When the race got under way, Yamamoto struggled early on in damp conditions, dropping to 14th place, before carving his way back up front after a red flag bunched up the field.
The 30-year-old claimed the final spot on the podium just six laps from the finish, overtaking the Sard Lexus shared by Heikki Kovalainen and Yuichi Nakayama into Turn 1.
Button said he and Yamamoto were braced for a second non-score in succession, having been taken out of the Okayama season opener by the sister Honda of Real Racing team.
"The first race was obviously looking really good until the accident," Button said. "So qualifying 12th for this race, we were disappointed.
"We were worried that we would leave with no points. So to get 12 points is very good."
Button took over from Yamamoto for the crucial middle stint, where he had to drive on slick tyres on a track that still had visible damp patches.
He said his previous experience of driving in the wet in Formula 1 helped his cause, although lapping GT300 cars in such conditions represented a new challenge.
"The first two laps I had 300s overtaking me because they had wet tyres. And then I got overtaken by the #64 [Nakajima Honda] car on wet tyres," said Button.
"Then when my tyres were warm I could start overtaking and obviously people were making mistakes. So staying out of trouble was good.
"It was really good fun. And my experience from Formula 1 in those conditions was perfect, it helped. It helped a lot.
"Normally with racing it's a bit of memory, but this is feeling everything, trying to find the grip.
"I always loved that in Formula 1 and I really enjoyed it [at Fuji]."
Asked to pinpoint why his team struggled in qualifying but finished as the top Honda in the race, Button said the NSX-GT had been "bouncing" around.
"We really struggled with bouncing with the car," he explained. "On the straight but also in the corners, the car is jumping a lot.
"We need to understand why because even in the race it was still a problem. It was better in the race but we still need to improve.
"So Naoki-san and myself need to discuss it and make improvements because this was a tough circuit for us and other Hondas were faster in qualifying."
Button and Yamamoto now sit fourth in the drivers' standings, 13.5 points behind championship leaders Ronnie Quintarelli and Tsugio Matsuda of works Nissan team NISMO.