Daniel Ricciardo was the early pace-setter in Bahrain after FP1, but Max Verstappen was unable to set a timed lap after an on-track stoppage within the first five minutes.
Only a tenth was separating Valtteri Bottas, Kimi Raikkonen and Sebastian Vettel at the top of the timesheet, until Ricciardo raced to the front with a 1:31.060 inside the final 15 minutes of the session on supersoft tyres.
His team-mate Verstappen, though, spent the vast majority of the session in the garage as his RB14 developed a suspected electronics issue.
Lewis Hamilton found himself down in P5 after a lock-up in the middle sector prevented him from narrowing the gap to the leaders.
Both Haas drivers, Romain Grosjean and Kevin Magnussen, finished in the top 10 and showed good early pace, whilst Pierre Gasly was in the lofty heights of P7.
Further down the leaderboard, Force India duo Sergio Perez and Esteban Ocon finished last of those who were able to set a timed lap.
After Formula 1 bosses revealed their latest 2021 vision for the sport on Friday morning, attention turned to the first free practice session for Bahrain Grand Prix in red-hot conditions.
One Red Bull car did not particularly like them as Verstappen lost all power within the first five minutes and had to push the RB14 for a short distance so the engineers could recover the car in the pit lane.
Ricciardo also briefly lost drive but was able to stay out and get amongst the early pace-setters in Bahrain.
— Red Bull Racing (@redbullracing) April 6, 2018
Turn 8 also proved to be a little problematic as Lance Stroll and Charles Leclerc suffered early spins, but luckily neither driver picked up any damage to their cars other than ruined tyres.
At the halfway point, it was Hamilton leading the way with a 1:32.532 on soft tyres, four tenths quicker than team-mate Bottas in P2. Verstappen still firmly in the garage after his very early stoppage.
The quickest supersofts then came out to play in the second half of FP1, with Mercedes and Ferrari continuing to lower the benchmark.
Yet it was Ricciardo who had the final say in the first supersoft battle and hit the front within the closing stages, making it a story of mixed fortunes so far for Red Bull.
FP2 gets underway at 1800 local time, where conditions will be much more representative of what is to come under the lights in the first night race of the season on Sunday.
1 Daniel Ricciardo Red Bull 1:31.060
2 Valtteri Bottas Mercedes 1:31.364 0.304
3 Kimi Raikkonen Ferrari 1:31.458 0.398
4 Sebastian Vettel Ferrari 1:31.470 0.41
5 Lewis Hamilton Mercedes 1:32.272 1.212
6 Romain Grosjean Haas 1:32.516 1.456
7 Pierre Gasly Toro Rosso 1:32.779 1.719
8 Carlos Sainz Renault 1:32.885 1.825
9 Kevin Magnussen Haas 1:32.971 1.911
10 Nico Hulkenberg Renault 1:33.104 2.044
11 Fernando Alonso McLaren 1:33.223 2.163
12 Charles Leclerc Sauber 1:33.278 2.218
13 Stoffel Vandoorne McLaren 1:33.364 2.304
14 Lance Stroll Williams 1:33.379 2.319
15 Sergey Sirotkin Williams 1:33.467 2.407
16 Brendon Hartley Toro Rosso 1:33.497 2.437
17 Marcus Ericsson Sauber 1:33.508 2.448
18 Sergio Perez Force India 1:33.662 2.602
19 Esteban Ocon Force India 1:33.794 2.734
20 Max Verstappen Red Bull No time set