No qualifying regrets for Hamilton
McLaren and Ferrari admitted errors in reading the weather at the Malaysian Grand Prix had left their drivers at the back of the grid for Sunday's race.
The teams decided to stay in the pits at the start of qualifying when the track was at its driest.
Lewis Hamilton, who will start, 20th, said: "Of course with hindsight we would have gone out earlier, but hindsight is a wonderful thing."
Ferrari's Fernando Alonso, 19th, added: "We need to avoid these mistakes."
Hamilton's team-mate Jenson Button will line up 17th, with the second Ferrari of Felipe Massa 21st.
Confidence is still high - Alonso
The teams were responding to a weather forecast that said the rain would stop a few minutes into the first 20-minute part of qualifying. Instead, the weather became progressively worse and their drivers' attempts to recover from the error were futile.
Hamilton said: "The simple fact is that we didn't expect it to rain any more.
"We went out at a similar time to the other top teams, and as a result quite a lot of us were all out of luck.
"By the time I got out there, there were lots of yellow flags about, so you just couldn't nail it - and then it started to rain more heavily.
"You couldn't feel a thing - it was so, so slippery. It was easy to come off - I had a spin on my first lap, in fact - but I did the best job I could in the circumstances."
Whitmarsh explains McLaren decisions
Button added: "We read it wrong basically. We thought that first rain storm was it and there was nothing else coming so we waited, and it was obviously the wrong thing to do.
"We can certainly make a race of it, though. This is exactly what Formula 1 wants, so the race should be good."
While Button spun off in the tricky conditions part-way through the session, Alonso and Hamilton made heroic attempts to scrape into the second session, but missed out by less than 0.2 seconds.
Alonso said: "We really thought the rain had finished so we waited in the garage but it got heavier. We were in the wrong place at the wrong time.
Ferrari team made a big mistake - Massa
"But the race is tomorrow. We saw last week in Melbourne that we can get results from the back of the grid so we will just have to make sure we do that."
The teams' decisions will come under heavy scrutiny because it has rained heavily at a similar time in the afternoon all week at the Sepang track.
BBC F1 pundit Eddie Jordan said there was "no excuse" for not going out at the start of the session to put in what is known as a 'banker lap'.
McLaren team principal Martin Whitmarsh said: "We were watching the radar and it showed us the rain was going to ease off so we were waiting for that to happen, but it didn't.
"We sent our cars out before Mercedes before Ferrari and before Mark Webber (who ended up on pole). Jenson got his quick lap in but then spun off so technically he actually got through.
"We and a few others probably regret that we stuck with our normal processes, but if you have got radars and information and processes then it makes sense to follow them.
"But sometimes maybe it is better to stick your hand out of the window and perhaps we should have done that this time."