The Australian driver, who's failed to even start his two grand prix in 2026 in his home town of Melbourne and then Shanghai, desperately needs a boost in the season's third race and received it as McLaren's pace confounded everyone on Friday.
The 24-year-old lapped the 5.8km Suzuka circuit in one minute 30.133 seconds, finishing 0.092sec ahead of Kim Antonelli, winner in China, and 0.205sec clear of F1 championship leader George Russell, the season's dominant Mercedes duo who were taken aback by the constructors champions' speed.
"Overall, it was a decent day for us," beamed Piastri, even if he was not about to get too carried away by McLaren's day-one showing after suggesting on Thursday they were still a second-per-lap slower than Mercedes.
He had finished fourth in the morning just behind teammate Lando Norris, who'd been third quickest in first practice, but really excelled in the afternoon as he topped the timesheets while the world champ proved fourth quickest.
"We felt like we made some good progress, particularly in the second practice session, which was encouraging," added Piastri.
"The feeling is positive, and we've gathered some valuable data that puts us in a solid position.
"We know there's still work to do, and it's clear that some of our competitors, especially Mercedes, are very strong.
"However, the focus is on our own performance. We hope to build on the progress from today and carry that momentum forward to be even more competitive."
Russell had finished fastest ahead of the 19-year-old Italian Antonelli in the first session but took close notice of Piastri's performance in P2.
"It was a little surprising to see the pace of McLaren but there is no reason to believe that it isn't genuine," he said.
"We've clearly got some work to do overnight to find some pace if we are to challenge them tomorrow."
There are still reliability concerns at McLaren, though, as Norris spent large parts of both sessions with his car being worked on in the garage.
Ferrari, the closest challengers to Mercedes in the opening two rounds, had Charles Leclerc and Lewis Hamilton fifth and sixth in both sessions.
Red Bull's four-time world champion Max Verstappen was seventh fastest in the opening session and 10th in the second.
25°C