Valtteri Bottas dominated the opening practice session for Formula 1's Spanish Grand Prix as Mercedes established an early advantage over Ferrari.
The Finn lapped 0.849s faster than teammate Lewis Hamilton, with Sebastian Vettel another tenth back in the best Ferrari despite using supersofts to the Mercedes drivers' softs.
Bottas and Hamilton established a Mercedes one-two early in the first half an hour broke into the high-1m18s on soft tyres, a feat nobody else managed over the rest of the session.
Ricciardo was third fastest initially, more than a second behind Bottas's early 1m18.695s benchmark, but then triggered a virtual safety car.
Conditions were clearly difficult as Bottas, Vettel and Marcus Ericsson all had early spins at different parts on the circuit before Brendon Hartley and Romain Grosjean took trips through the Turn 4 gravel.
They were fortunate to emerge unscathed, particularly Hartley, whose Toro Rosso skated right up to the edge of a barrier on the outside of the gravel, but Ricciardo was not so lucky.
The Red Bull driver had a wobble entering the same corner and took to the gravel, running straight across and nudging the barrier hard enough to break the front left.
When the virtual safety car finished, Bottas improved twice on a new set of soft tyres and got down to a 1m18.411s before another Turn 10 moment, this time locking up and running deep after encountering traffic.
Further incidents ensued as drivers grappled with the tricky circuit, with both Williams drivers falling foul in quick succession.
Reserve driver Robert Kubica's first FP1 outing of the year in place of Sergey Sirotkin featured a lethargic spin at Turn 13, before Lance Stroll posted a personal best first sector then promptly beached his car in the Turn 5 gravel.
A few minutes before that off, Stroll had complained over the radio that it was "unbelievable how bad the balance is, I just want a little bit of understeer".
That caused a second virtual safety car and when that ended, Bottas improved his benchmark yet again.
Bottas set new best times in all three sectors to post a 1m18.148s, while Hamilton did not improve after switching to mediums.
McLaren earned best-of-the-rest honours as it debuted a striking new nose and updated bargeboards, with Fernando Alonso 1.7s off the pace.
That shuffled Ricciardo to seventh, with Romain Grosjean, Stoffel Vandoorne and Pierre Gasly completing the top 10.
Vandoorne's McLaren has a new Renault energy store fitted for this weekend, which means another change this year will result in a grid penalty.
|4||Max Verstappen||Red Bull||TAG||26||1'19.187||1.039|
|7||Daniel Ricciardo||Red Bull||TAG||11||1'19.871||1.723|
|10||Pierre Gasly||Toro Rosso||Honda||29||1'20.508||2.360|
|13||Sergio Perez||Force India||Mercedes||36||1'20.924||2.776|
|16||Esteban Ocon||Force India||Mercedes||27||1'21.144||2.996|
|18||Brendon Hartley||Toro Rosso||Honda||28||1'21.373||3.225|