Championship leader Lando Norris set the second practice pace at the Las Vegas Grand Prix before the end of the session was curtailed by a precautionary check on a manhole cover.
After McLaren's pre-event concerns that the Las Vegas Strip Circuit may again not play to their strengths appeared to be realised during Friday's earlier first session, Norris was back on the pace in second practice and set a day-best time of 1:33.602 to outpace Mercedes' in-form Kimi Antonelli by 0.029s.
However, the final timesheet came with a significant caveat given neither of Norris' two title rivals - Oscar Piastri and Max Verstappen - the two Ferraris nor Mercedes' George Russell, last year's dominant race winner, completed their own laps on the soft tyre.
The red flag was first thrown with 21 minutes left on the clock after a trackside marshal reported a possible loose manhole cover before Turn 17.
With Race Control unable to confirm whether or not that was the case via CCTV, personnel were sent down to assess that part of the track once all cars were back in the pit lane.
Once those checks were completed, the session resumed with just under six minutes left. However, the red flags were back out three minutes later and that second stoppage brought an effective end to the session.
"Some Race Control personnel remained on-site when the session was restarted," read an FIA statement.
"They reported that the manhole cover was moving as cars passed over it, which led to the session being ended under red-flag conditions. Further inspections are under way."
F1 Academy's qualifying session took place as scheduled afterwards.
The inaugural practice session on the Vegas street circuit back in 2023 was infamously heavily disrupted within minutes of it starting by a loose drain cover, which did heavy damage to Carlos Sainz's Ferrari and caused delays of several hours to the rest of the night-time schedule.
While there was little chance for any running between Friday's red flags, there was still enough time for Leclerc - the Practice One pacesetter - to park his Ferrari at the side of the track with a suspected gearbox problem.
Leclerc still finished third on his medium tyres ahead of Sauber's Nico Hulkenberg and the Racing Bulls of Isack Hadjar and Liam Lawson.
Of the other drivers to finish without a soft-tyre lap, Russell was seventh, Verstappen ninth, Lewis Hamilton 10th and Piastri 14th.
Pacesetter Norris, who leads Piastri by 24 points in the standings, said: "I think we have a better feeling in the car than last year. That was felt on lap one.
"Some good feelings. Not a lot of running in the end, not really any high fuel running, but the pace is there.
"It's pretty tight between a lot of people and many people didn't get their laps in. We made some steps forward from FP1 to FP2 and hopefully we can do some more.
"We are fighting for pole."
Several hours earlier and Leclerc made a flying start to the Las Vegas Grand Prix weekend for Ferrari by setting the pace in first practice.
But the opening session proved a challenging one for McLaren with title leader Norris and main rival Piastri, his team-mate, finishing only sixth and eighth fastest respectively.
Zak Brown, McLaren's chief executive, told SportNews F1 from the pit wall during the session that the team were braced for a "tricky weekend" on a track they are yet to finish on the podium.
Norris twice ran off track and once brushed the wall during the opening hour of running, although still finished two tenths faster than his team-mate when he did get a lap together on soft tyres.
Leclerc, a podium finisher in Vegas last year, was quick out of the blocks on both the medium and soft tyres to finish up with a best time of 1:34.802.
Williams also made a strong start, with Alex Albon 0.166s back on Leclerc in second and Sainz fifth, with the Red Bull pair of Yuki Tsunoda and Verstappen finishing in between them in third and fourth.
Hadjar split the McLarens in seventh for Racing Bulls with last year's winners, Mercedes, only ninth and 10th with Russell and Antonelli respectively.
With the first session on the Strip Circuit proving challenging for drivers amid a low-grip track street track surface and chilly late-afternoon conditions, numerous drivers ran off track during the opening hour when they missed their braking points - including Hamilton, who was 11th in the second Ferrari.
Saturday November 22
12.15am: Las Vegas GP Practice Three (session starts at 12.30am)*
2.10am: F1 Academy Race One*
3am: Las Vegas GP Qualifying build-up*
4am: LAS VEGAS GP QUALIFYING*
6am: Ted's Qualifying Notebook*
Sunday November 23
12.15am: F1 Academy Race Two
2.30am: Grand Prix Sunday: Las Vegas GP build-up*
4am: THE LAS VEGAS GRAND PRIX*
6am: Chequered Flag: Las Vegas GP reaction*
7am: Ted's Notebook*
*also live on SportNews Main Event
Formula 1's thrilling title race continues with the Las Vegas Grand Prix this weekend, live on SportNews F1.
