Liam Lawson failed to secure the Super Formula title at Suzuka, finishing runner up to Ritomo Miyata.
The Red Bull Junior's chances were dampened following a dramatic crash during the first race of the weekend at 130R between Hiroki Otsu and Ukyo Sasahara.
Lawson started from seventh on the grid and climbed up to sixth before the race was stopped after five laps due to the heavy crash, with Otsu walking away without injuries while Sasahara was treated for concussion.
During the final race Lawson finished in second, but it was not enough to outscore Miyata in third who managed to win the title by just eight points.
The 21 year-old was the substitute for Daniel Ricciardo for five races, after he broke his metacarpal during practice for the Dutch Grand Prix.
“I knew it was going to be tough swapping back to Super Formula after driving the F1 car and it was," he told Red Bull.
"It was great to get the Teams' championship, a shame we didn't take the Drivers' title as well, especially for my side of the garage who worked so hard and supported me so completely."
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Lawson: A frustrating day for all
Lawson was hoping to wrap up the Super Formula title before returning to his role as Red Bull reserve in 2024, after impressing at the wheel of the AlphaTauri.
But he knew it would be an uphill struggle after making a mistake in the first qualifying session, which put him outside of the top five.
"We knew going into the final weekend we had points to make up and Q1 on Saturday was OK, put in a banker lap," he explained.
"In Q2, I was 95% round my push lap that would have been right at the front when the red flag out.
“Because of the Motegi crash, I didn't have another set of tyres to have another go so that was it, P7.
“Still we could have got something out of Saturday's race, I was moving forward, made a couple of passes but then the race was red-flagged and I actually lost points.
"A frustrating day and all the more so considering we took pole on Sunday. We didn't find more pace on Sunday, we had that pace on Saturday, it was just the circumstances that meant we didn't show it.”