Oscar Piastri was quickest in a chaotic Japanese Grand Prix second practice, during which a huge Jack Doohan crash caused one of four red flags.

Piastri, who finished practice with the fastest time of 1:28.114, was 0.049 seconds quicker than team-mate Lando Norris as McLaren continued their early-season dominance.

However, four lengthy interruptions saw the drivers limited to just 20 of the scheduled 60 minutes.

Doohan had not driven in first practice and then lost control of his car at the first high-speed corner, shunting the barrier and losing two wheels in the process, causing a delay of around 20 minutes.

Alpine confirmed after the session that Doohan was "OK" following a visit to the medical centre and did not suffer a concussion after the crash.

Shortly after the restart, Fernando Alonso was beached in the gravel after a spin in the windy conditions, with the last two red flags due to the grass at the side of the track catching fire from sparks flying off the floors of cars.

In the action that did occur, Piastri found the edge over Norris, who had topped the first practice, with no other teams able to get close to this season's early pace-setters.

Piastri remained confident after practice but warned McLaren that they cannot let their guards down.

"With part of the track being resurfaced and gusty winds, it's been a challenge," Piastri said.

"When it's gusty, you don't have the same car two laps in a row, so it's been a tricky day.

A positive session despite limited running #McLaren | #JapaneseGP pic.twitter.com/48eYQ9edTM

— McLaren (@McLarenF1) April 4, 2025

"FP2 was stop-start, so it was hard to get into a rhythm, but by the end of the day, it felt reasonably comfortable. Still some fine-tuning to go; some things I've been happy with today, but it hasn't been the easiest overall.

"Mercedes look quick, just didn't find much on the softs, and in this kind of session, it's difficult to get a proper read. I'm confident we have good pace for the rest of the weekend, but we still have to be on our toes."

Racing Bulls drivers Isack Hadjar and Liam Lawson finished third and fifth, with Lewis Hamilton splitting them.

George Russell, who had finished second in first practice, was 0.453s behind Piastri's time in the second, finishing in sixth and sitting above Charles Leclerc and Max Verstappen.

Like Piastri, Norris also remains wary of the threat Mercedes could pose, and is expecting a tough test in qualifying.

"I still think we are at the top. George was very quick this morning, just as quick as us. Mercedes are in a good place," Norris said.

"Red Bull look a bit further off, but they have looked further off into qualifying, then get closer again. So, it's normal, but it was a messy session. This was not a good example of where everyone was; maybe FP1 was a better example when you saw teams in order.

"I still expect it to be close and a close battle tomorrow. I hope it's not. I hope it's nice and easy, but I'm sure Mercedes, at least, definitely George from today's showings, will be challenging us tomorrow."