Sato has joined Nakajima for this week's post-season test at Suzuka ahead of an anticipated switch to the team for 2023, following an up-and-down rookie season driving for Team Goh with Red Bull backing.
Although he beat teammate Atsushi Miyake to Rookie of the Year honours, Sato did not do enough to convince Red Bull to give him a second chance in Europe, and the uncertainty surrounding Team Goh's future meant it looked like he may have been without a seat for 2023.
However, Toshiki Oyu's decision to leave Nakajima opened up a spot for Sato, who topped the opening session of the two-day Suzuka test with a best time of 1m36.117s, which was enough for sixth overall.
Katoh, who engineered Alex Palou in 2019 and has spent the last two seasons working with Yamamoto, was assigned to Sato on Wednesday as part of a swap between Nakajima's two car crews.
Asked for his opinion on Nakajima's newcomer, Katoh said he was impressed with Sato's speed, and felt he could have gone even faster without some extenuating circumstances.
"Naoki entered the 1m35s range in the afternoon, but there were quite a few places where Ren was faster," Katoh told Motorsport.com's Japanese edition. "For example, Ren is extremely fast at Degner.
"In that sense, he is in no way inferior to Yamamoto; he is a driver with serious potential. He’s really talented.
"At the time [Sato set his best lap] it was the first time this week we were using new tyres, I don’t think we were able to exploit the car fully, and in the afternoon the tailwind was stronger, which meant in the morning we didn’t have as much downforce in the S-curve.
"Also, in the morning, the pedals were hard enough to make him step on the throttle while braking, so there were times when he would lock the front of the car. That time was achieved under those circumstances."
Sato's day came to an early end with a crash at Degner Curve, which Katoh explained was due to a gear selection problem.
"I would have liked to see him try new tyres in the afternoon," he said. "It seemed he wasn’t able to downshift properly; he wasn’t able to go below fourth gear at the time he went off the track."
Sato's Degner crash was his second of the day, as he suffered an off at Turn 2 late in the morning session while trying to avoid another car, something he admitted was his own error.
"There was a car on its out lap that moved to the outside at Turn 2, and when I tried to avoid him, I went off and touched the barriers lightly," he said.
"In this test, there are some drivers who are not yet familiar with the car, so I should have been more careful. It was my mistake."
