Hamilton is three points clear of Vettel, who is not leading the championship for the first time this season.
When asked what a realistic result would be, Hamilton sounded deflated.
"It's still better than the original contract I had", he said.
"We knew coming into this weekend they would be strong but they were clearly the quickest today".
As it turned out the 30-year-old German did not ultimately need to risk all, as his provisional fastest would have been good enough for the top spot. The final lap wasn't great.
When he'd finally finished screeching, a breathless Vettel praised his team in Italian over radio, shouting "Grande Lavoro!"
"I believe Singapore won't be our only chance but is one of our best chances of a win in the second half of the season", Ricciardo, who won the Azerbaijan Grand Prix in June, had said in the build up to the weekend. The vehicle was fantastic, awesome track, if you feel the auto is coming alive and you can do what you want to.
Some contrast to his mood on Friday night.
The final practice session gets underway at 18:00 local time on Saturday before qualifying at 21:00.
The overnight transformation worked wonders.
Vettel's sensational time of 1min.39.491sec. was the fastest ever pole position time in either of the three configurations of the circuits used since the debut of the event in 2008.
"I don't know where Ferrari have picked up that pace", he added.
Mercedes will be the ones having a sleepless night this time. His teammate Lewis Hamilton is now leading the chart. Nine cars headed out first, including both Ferraris led by Raikkonen, and everyone was on ultrasofts.
Red Bull team principal Christian Horner hailed his drivers' efforts, and said the fact they are not in world championship contention could count in their favour come Sunday. Vettel will expect to be able to exploit it on Sunday. I think we've got a good package.
Mercedes chief Toto Wolff said the German marque faced a hard weekend - but he will take heart from the fact that in five of the last seven seasons, the winning driver in Italy also took the chequered flag in Singapore.
The Red Bulls will take some beating, too.
Max Verstappen led the charge for Red Bull-Renault to join Vettel on the front row.
No wonder the mood in the Mercedes garage was glum.
But not to this extent.