Kimi Raikkonen heads final Spanish Grand Prix practice
Kimi Raikkonen headed a Ferrari one-two in final practice at the Spanish Grand Prix with Lewis Hamilton third quickest for Mercedes.
Ferrari, with Sebastian Vettel 0.242 seconds slower than Raikkonen, turned the tables on Mercedes after Hamilton set the pace in both Friday sessions.
Hamilton was 0.381 seconds slower than Raikkonen, with Bottas a further 0.273secs off after engine problems.
The Finn missed three-quarters of the session as Mercedes changed his engine.
The team discovered a water leak in the new engine that had been allocated for Bottas this weekend and needed to replace it with the one he used in the first four races. Bottas got out at the end of the session for one run.
Vettel also ran into engine problems at the end of the session - the German, who is leading the championship by 13 points, stopped in the pit lane when heading out for a final run and had to be pushed back to the garage.
Ferrari said there was "no real engine issue, but we are replacing some parts precautionally" before qualifying, which starts at 13:00 BST.
Red Bull's Max Verstappen was fifth quickest from team-mate Daniel Ricciardo, the Dutchman who won this race last year just 0.157secs off Bottas and 0.654secs slower than Raikkonen, apparently confirming that the team have made a significant step towards the pace with an upgrade for this race.
- Predict your top three for qualifying
- Hedonism, history and Arnie's neck - F1 heads to Barcelona
- Rain in Spain? Your F1 forecast
But Mercedes have the most dramatic-looking modifications, with a series of new aerodynamic parts in the front half of the car.
The silver cars dominated Friday running, fastest on both one lap and with an even more of an advantage on the long runs, on which teams simulate race pace.
Renault's Nico Hulkenberg took seventh, 0.645secs off the Red Bulls and ahead of Williams' Felipe Massa, Toro Rosso's Carlos Sainz and McLaren's Fernando Alonso.
The Spaniard was just 1.879secs off the pace, a much better start to the day for McLaren and engine partner Honda than on Friday, when Alonso suffered a massive engine failure on his very first lap out of the pits.
Afterwards, the Spaniard brushed off an attempt by Honda F1 boss Yusuke Hasegawa to talk to him, as his frustrations with Honda's under-performance mount.