Lewis Hamilton said he experienced a "difficult day" of practice at the Saudi Arabian GP after finishing only eighth fastest and collecting a warning for impeding Logan Sargeant in a high-speed near-miss that Mercedes were fined for.
The seven-time champion and team-mate George Russell experimented with different set-ups on Mercedes' W15 on the opening day of 2024's second race weekend, with the latter finishing higher up on the Practice Two timesheet in a session topped by Aston Martin's Fernando Alonso.
Hamilton, who finished eighth quickest, was the subject of a post-session investigation after a high-speed near miss with Williams' Sargeant, who had to take evasive action at Turn 11 to avoid what stewards reckoned would have been a "serious, high-speed crash" on the wall-lined street track.
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Mercedes were fined €15,000 (£12,800) for not informing Hamilton about the oncoming car, while the driver himself received a warning.
Reflecting on his Thursday, Hamilton said: "A difficult day. Just lacking confidence in the rear of the car and the set-up.
"We did some work from session to session, changed the car quite a bit, but the underlying issue with the rear end that I was struggling with.
"So I had a couple of really big moments out there. In these high-speed areas you need to have full faith in the rear of the car, and I've just not got that yet."
Hamilton's fastest time of the representative floodlit evening session after the soft-tyre runs was 0.447s slower than Russell's.
"We're going to have to go through the data and stuff, but George is obviously a lot happier with his car," added Hamilton, who finished seventh in last week's Bahrain season-opener.
"We kind of went in different directions today. We're all trying different things to try to find the right solution for the car.
"But yeah, all I want is a stable rear, and then I'll be happy. So that's what I'm working on."
Second-fastest Russell, who finished one tenth ahead of runaway Bahrain GP victor Max Verstappen and 0.230s back on Alonso, said: "For sure Max is the quickest, Checo [Perez] is not too far behind.
"But it's difficult to follow at the moment. The cars are becoming increasingly harder to follow as the years progress and I think it's going to be tight again as we saw in Bahrain. Ferrari and Aston probably look like our biggest threats and rivals at the moment, but I think it's going to go down to qualifying again."
Alonso admits Aston 'definitely had a good Thursday'
Alonso, who has not won an F1 race for over a decade, was quick throughout Thursday and was also fast in Jeddah last year for Aston Martin.
However, the Spaniard alluded that he was on a different programme to the other top teams which exaggerated Aston Martin's pace.
"I feel good. Obviously it's only free practice, as we saw last year, and also in Bahrain. We were faster in free practice than in qualifying," said Alonso.
"I think we ran a different strategy in terms of fuel loads, engine modes and so on. We keep our programme ahead, not really any issues with the car, set-up possibilities also quite open for [Friday]. But definitely a good Thursday for us."
Verstappen expects 'very tight qualifying'
As for Max Verstappen three tenths adrift of Alonso in the only representative practice session under the lights in Jeddah.
Verstappen dominated the season-opener from Red Bull team-mate Sergio Perez but the field appear to be closer in Saudi Arabia, even on Thursday's long runs.
"I think it's been pretty good overall. Of course, this track is always a bit more slippery, but I have to say they prepared the track quite well, to be honest, for like a street circuit. It wasn't too dirty," explained Verstappen.
"The pace has been alright. FP2 - long run, short run, I think overall we learned a lot again. Of course, there are always things you look at to do better over one-lap performance, but also I think some teams already used a little bit more power, like they did in Bahrain, so we take that also into consideration.
"But when we went into the long runs, it looked again quite nice. So I'm quite happy with that. I feel quite good (about qualifying) but it will be again very tight. I think that is probably where other people are a bit better than us, over one lap, and our car probably comes a bit more alive on the long run."
Sky Sports F1's live Saudi Arabian GP schedule
Friday March 8
- 11.55am: F1 Academy Race 1
- 1.10pm: Saudi Arabian GP Practice Three (session starts at 1.30pm)
- 3.05pm: F2 Sprint Race
- 4.10pm: Saudi Arabian GP Qualifying build-up
- 5pm: SAUDI ARABIAN GP QUALIFYING
Saturday March 9
- 12pm: F1 Academy Race 2
- 1.20pm: F2 Feature Race
- 3.30pm: Saudi Arabian GP build-up: Grand Prix Saturday
- 5pm: THE SAUDI ARABIAN GRAND PRIX
- 7pm: Saudi Arabian GP reaction: Chequered flag
- 9.30pm: Saudi Arabian GP highlights
Watch the second round of the new F1 season - the Saudi Arabian GP - live on Sky Sports F1 this coming week, with qualifying on Friday and the race at 5pm on Saturday. Stream every F1 race and more with a NOW Sports Month Membership for just £21 a month for 12 months
Anthony Joshua's heavyweight showdown with Francis Ngannou takes place on Friday March 8, live on Sky Sports Box Office with the main event expected around 11pm. Book Joshua v Ngannou now!
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