Max Verstappen topped the one session of dry practice running that took place on an otherwise rain-affected Friday at the Japanese Grand Prix, while Williams suffered a fresh setback.
With world championship leaders Red Bull bringing their first significant car upgrade of the season to Suzuka, Verstappen led team-mate Sergio Perez in a one-two at the head of the Practice One timesheet ahead of Ferrari's Melbourne victor Carlos Sainz in a session that saw Logan Sargeant crash out in his Williams.
But there was no significant running in Practice Two as rain arrived before the session and then continued during the hour, with only a handful of lap times completed by drivers as a result.
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Improved conditions in the closing minutes did allow a brief window of dry-tyre running. McLaren's Oscar Piastri was one of those to take up the opportunity and the Australian clocked the second session's nominal fastest time of 1:34.725, four seconds slower than Verstappen's earlier pace in the dry.
Verstappen was one of seven drivers to sit out the entirety of the second practice.
Those seven included Sargeant, although the American driver's absence was enforced owing to the "extensive" damage his Williams car had suffered from his Practice One accident at the fast Dunlop corner.
The one solace for Williams was that the American at least did not miss out on any representative running.
Friday's condensed running now sets up a busy Saturday for the whole field, with final practice at 3.30am ahead of qualifying at 7am, live on Sky Sports F1.
Crucially, teams will also have less data to lock in their set-up choices for qualifying and Sunday's race than is usual for what is the first-ever spring-time Japanese GP.
"The biggest thing that excites me for the rest of the weekend is the teams don't have long run data, unless they did it in P1," said Sky Sports F1's Bernie Collins, a former race strategist.
"They are going into a race in Japan with cool conditions with no knowledge and that leaves us with a very interesting race on Sunday."
What happened in the dry Practice One?
While Verstappen began his attempt to return to winning ways after his shock Melbourne retirement in perfect fashion by leading a Red Bull one-two in an upgraded RB20, the beleaguered Williams team suffered another unwanted setback two weeks on from their own travails in Melbourne.
It was the corresponding practice session in Australia when a heavy crash for Alex Albon had written off his car and left the team, without a spare, with only one useable chassis for the remainder of the event.
Albon, consistently the team's fastest driver, was subsequently given Sargeant's car, with the American withdrawn from the weekend. The damaged chassis was flown back to the UK for repairs before being flown back out for this weekend's Suzuka event.
It was that repaired chassis that Sargeant damaged when he spun off track at the start of his first soft-tyre run at the fast Turn Seven.
"Luckily he's gone in with the nose of the car first," said Sky Sports F1's Anthony Davidson after replays showed Sargeant straying wide onto the grass on the exit of the left-hander and then losing control on the gravel.
"I'm not seeing any damage around the suspension area. If that was side impact, I dread to think what that chassis would have gone through yet again."
Williams have said they are set to remain without a spare chassis until May's Miami GP in two races' time.
The accident brought out the weekend's first red flag just before opening practice's halfway point and, when the session did resume, Verstappen hit the front when he put on the soft tyres with a quickest lap of 1:30.056.
"It was a good start for us," Verstappen said. "The balance wasn't too far out which is always a great way to start but it does look like everyone is a bit closer compared to last year. There are still a few things to look at and try but, overall, quite happy with first practice."
Perez finished 0.181s back in the sister car, with the in-form Sainz close behind in the lead Ferrari in third.
"Practice One was a bit closer to the Red Bulls than anticipated, so positive signs in terms of progress made from six months ago to now," Sainz said.
"You don't know fuel loads and engine modes but last year we were eight tenths off in qualy and here, to be two tenths off in Practice One, is a good feeling and starting base. But they [Red Bull] are going to be difficult to beat this weekend."
After a woeful Melbourne, when they were again off the pace and registered their first double DNF for six years, Mercedes could take early encouragement from the running in Japan too with George Russell and Lewis Hamilton between the two Ferraris in fourth and fifth respectively.
"The drivers look more comfortable on track than they did in Melbourne," said Davidson.
"That Mercedes splitting the two Ferraris and only four-and-a-half tenths away from a heavily-upgraded Red Bull with Verstappen putting a sweet lap in, for me that's the surprise of the season."
Hamilton ran a new power unit in the opening session after Mercedes confirmed on Friday morning that the one that failed on his W15 in Melbourne could not be used again.
Charles Leclerc was sixth in the second Ferrari, with Fernando Alonso the lead Aston Martin in seventh, despite team-mate Lance Stroll, who was 15th, running the new sidepods the team have brought to Suzuka. That meant Aston Martin were back-to-backing old and new designs in the opening session.
McLaren briefly topped the timesheet earlier in the session but were eventually shuffled down to eighth (Piastri) and 10th positions (Lando Norris) having had to abort their initial soft-tyre runs for Sargeant's shunt. Japan's Yuki Tsunoda was in between them in ninth for RB.
Red Bull's sister team fielded an all-Japanese line-up in the opening session as junior driver Ayumu Iwasa, 22, was given his debut F1 practice run-out in Daniel Ricciardo's car. Iwasa, who finished fourth in last year's F2 championship, completed 22 laps and finished with the 16th-fastest time, lapping nine tenths slower than Tsunoda.
Ricciardo returned to his car in the second session and completed more laps than anyone, nine, in the on-off rain.
Sky Sports F1's live Japanese GP schedule
Saturday April 6
3.15am: Japanese GP Practice Three (session starts at 3.30am)*
6am: Japanese GP Qualifying build-up*
7am: Japanese GP Qualifying*
9am: Ted's Qualifying Notebook*
9.30am: Japanese GP Qualifying replay
Sunday April 7
5am: Grand Prix Sunday Japanese GP build-up*
6am: The JAPANESE GRAND PRIX*
8am: Chequered Flag: Japanese GP reaction*
9am: Ted's Notebook*
9.30am: Japanese Grand Prix highlights*
10.30am: Japanese Grand Prix replay
*also live on Sky Sports Main Event
Formula 1's biggest ever season continues with the Japanese Grand Prix, live on Sky Sports F1 this weekend. Stream every F1 race and more with a NOW Sports Month Membership - No contract, cancel anytime
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