The Finn overcame some lost time in free practice one to a floor change to set the fastest time of the day — a lap of 1 minute 38.699 seconds — to beat title leader Lewis Hamilton by just 0.011 seconds.
“For sure it could have been even a bit better,” Raikkonen said. “I went on the kerbs on the fastest lap, so I lost quite a bit of time.
“I think it will be close [with Mercedes]. We just need to get things in order, fix a few areas, but I think the tyres were what we expected and seemed to work pretty okay.”
But Hamilton’s proximity to the Finn was a particularly pleasing result for Mercedes given it has struggled for pace in Singapore in recent seasons. The Silver Arrows notably spent the first practice session focusing on long-run pace on the durable soft-compound tyre, shunning the qualifying hypersoft tyre for the entire 90 minutes.
Vettel, Hamilton’s only remaining championship challenger, didn’t set a representative time after he crashed during his qualifying simulation run.
The German slid sideways into the barriers on the exit of the penultimate corner, and though there was little visible exterior damage, his Ferrari began spilling pink radiator fluid as he limped back to the pits 43 minutes into the 90-minute practice session.
His team wasn’t able to complete repairs with enough time to send Vettel out again, ending his evening early.
“Obviously it was a bit more than just a kiss!” the four-time Singapore winner said. “We lost some time, which is not ideal, but nevertheless I think I got a good feel for the car.
“Tomorrow I think it will be key to find the right balance and to feel the car a little bit better than this evening.”
With Vettel out of the picture at the top of the time sheet, Max Verstappen and Daniel Ricciardo were able to set the third and fourth-fastest times, but the Red Bull Racing drivers were more than half a second off the pace.
Though Ricciardo said is team demonstrated strong race pace, he admitted qualifying remained a concern.
“On the tyres we’re looking as good if not better than everyone, but if we don’t qualify in the top two or top three, it’s probably not that important,” he said.
“Qualifying is nearly as important as Monaco around here. Race pace is all right, but we’ve got to sort out the one-lap pace.
“I think we will, but a bit of work to do tonight.”
Valtteri Bottas ended the day fifth and 0.669 seconds off the pace, but the Finn compromised his fastest lap by running wide out of the last corner.
Carlos Sainz led the midfield for Renault, albeit with a time 1.5 seconds slower than Raikkonen’s headline lap. The Spaniard kept at bay Haas’s Romain Grosjean and McLaren’s Fernando Alonso, the trio separated by one-tenth intervals.
Vettel finished ninth after his crash, and Renault’s Nico Hulkenberg completed the top 10.
Force India brought a significant update package to Singapore, but its performance on the slow and twisty circuit was uninspiring. Sergio Perez was 11th and more than two seconds off the pace; Esteban Ocon was one-tenth slower in 13th.
Sauber ended the day with Marcus Ericsson and Charles Leclerc in 12th and 14th respectively ahead of Haas’s Kevin Magnussen and McLaren’s Stoffel Vandoorne.
Toro Rosso was disappointed to end the day 17th and 18th given expectations the slow circuit would suit the underpowered Honda engine and the team’s efficient chassis, but neither Brendon Hartley nor Pierre Gasly could lap within 0.4 seconds of the rest of the midfield.
Williams ended the day slowest, with Lance Stroll leading Sergey Sirotkin in 19th and 20th.