Lewis Hamilton has warned Mercedes about making too many changes and 'messing it up' ahead of the Japanese Grand Prix this weekend.
The Briton has endured a difficult start to the new season, experiencing difficulties in Bahrain, Saudi Arabia and Australia so far.
Yet Hamilton was happy after finishing fifth in P1 on Friday, with team-mate George Russell one place higher.
Speaking to Sky Sports in the aftermath of the race, the 39-year-old was upbeat.
Lewis Hamilton has warned Mercedes not to make changes and 'mess it up' ahead of the Japanese Grand Prix
SKY
"It was a great session, the best session we've had this year and the best the car has felt this year so far," said the seven-time F1 champion.
"It felt really positive. Exciting. It's a circuit that every driver loves to drive.
"In the last couple of years, we've had a really difficult car and balance to drive here.
"Given the difficult last few races we've had, great work has been done in this past week and we have seemed to hit the ground in a bit more of a sweeter spot.
"I haven't made any changes since."
Yet while Hamilton was upbeat, he's warned the team not to make 'too many changes and mess it up'.
"It's hard to know," he added when asked about his prospects of securing glory this weekend.
"I think we have a better baseline to start from so as long as we don't make too many changes and mess it up, I think we'll probably stay where we are.
"It's a shame we didn't get that session.
"They have changed the tyre rules so no one runs on the intermediate, which doesn't make sense really."
Russell has also provided his verdict after P1.
And Hamilton's Mercedes team-mate has admitted their success was a 'pleasant surprise', with the 26-year-old saying: "FP1, we definitely performed better than we expected, so that was a pleasant surprise.
"The car was feeling really nice to drive and Lewis and I were really happy with the balance.
"It has been performing better when it's been slightly colder, but we've been doing a lot of test items to try to make that car a little bit more consistent when conditions are variable, so time will tell."
He added: "It's going to be very challenging because it's a clear one-lap tyre in qualifying, you can't do multiple laps on the tyre.
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Lewis Hamilton finished fifth in P1 ahead of the Japanese Grand Prix
GETTY
"Most drivers may only have three or four sets of qualifying, so you've got to be nailing those laps at every opportunity if you want any hope of getting into Q3 with two sets of new tyres.
"I think you're going to see quite high degradation, and that's where the focus is going to be."
Verstappen, meanwhile, was pleased with his own performance after finishing fastest.
"It was a good start for us," said the Dutchman.
"The balance wasn't bad and that is always a good way to start.
Max Verstappen was pleased with his performance in P1 as Red Bull eye Japanese Grand Prix glory
GETTY
"It seems like everyone is a little closer together compared to last year.
"I think in general over one lap, it seems like people have got closer, but for the long run pace, I have no idea, but I don't expect gaps like there were last year here.
"We couldn't do anything in the second free practice session, but there are still a few things we have to look at and try out.
"But in general, I am quite satisfied with the first session."