Team Mugen's Tomoki Nojiri outpaced Yuhi Sekiguchi by just 0.032 seconds to top a rain-affected second day of Super Formula's rookie test at Suzuka.
With rain hitting the track in the final 40 minutes of the morning session and returning again in the afternoon, most of the day’s quickest times were set earlier in the day.
Wednesday pacesetter Nirei Fukuzumi (Dandelion) was the first to break the 1m38s barrier, clocking a time of 1m37.792s at the 30-minute mark to move to the top of the timesheets.
European F3 racer Alex Palou (Nakajima) and former Formula 1 driver Kamui Kobayashi (KCMG) bettered Fukuzumi's time in the next 15 minutes, before Nojiri seized control with a 1m37.297s.
That time would remain unbeaten for the rest of the day, with Sekiguchi coming closest of all in the Impul Toyota.
Kobayashi’s previous lap of 1m37.398s put him third-quickest at the end of the day, just over a tenth down on Nojiri’s chart-topping time, while Palou’s early effort was good enough for fourth.
Ryo Hirakawa ended up fifth in the second of the Impul cars, 0.086s clear of Fukuzumi.
Dominant 2018 Japanese F3 champion Sho Tsuboi caused an early red flag when he spun his Inging Toyota at the hairpin, but was able to return to the pits on own power shortly afterwards.
He ended the day just behind his teammate Hiroaki Ishiura in eighth but ahead of TOM’S pair Kazuki Nakajima and Nick Cassidy.
Red Bull junior Dan Ticktum, who is now confirmed to race in Super Formula next season, was classified just half a tenth behind Cassidy in 11th and 0.891s off Nojiri’s pace.
Defending champion Naoki Yamamoto could only muster the 20th-fastest time of the day after running into electrical issues in the morning, when the track was at its best.
Elsewhere, Ralf Aron tested for Kondo Racing in place of regular driver Kenta Yamashita, having driven for Team LeMans in yesterday’s test.
Apart from Tsuboi, several other drivers prompted red flags, most notably F2 race winner Tadasuke Makino, who crashed at the Esses and damaged the front wing of his Nakajima Honda.
Additional reporting by Tomohiro Yoshita
Day 2 results:
|15||Charles Milesi||Team LeMans/Toyota||1’39.212||1.915|
|17||Tristan Charpentier||Real Racing/Honda||1’40.216||2.919|
|19||Arjun Maini||Team LeMans/Toyota||1’40.779||3.482|
|21||Yoshiaka Katayama||Team LeMans/Toyota||1'42.225||4.928|