Relief was the overriding emotion from McLaren's director of engineering Tim Goss in the wake of victory in Australia. "We could see we were quick in testing, but so were Red Bull, Mercedes and Lotus," he said.
"We had no way of knowing exactly how we all compared, because none of us has the relevant detail data for the others. So we didn't know if we were going to be starting from seventh and eighth or first and second."
Hamilton has a decisive edge over Vettel in sector 2, but not elsewhere © LAT
For Sepang he can be fairly confident his drivers won't be starting from seventh and eighth. Friday practice suggests the MP4-27 is again the class of the field here, and though it might have a rival for the front row in Mercedes and a rival for race pace in Red Bull, as a combination of the two demands, the McLaren appears to have it sewn up.
It then becomes a question of track positioning - for if a Mercedes or two does get ahead at the start, restricting the McLarens to their pace, then that's great news for Red Bull.
With the proviso that the Lotus hadn't shown its expected pace during Friday and that there could be much more to come from it, the main contenders - McLaren, Mercedes and Red Bull - have sharply distinctive performance profiles.
The McLaren is around 0.5 seconds adrift of the Mercedes in the straightline speed zone that is sector one, and those positions are reversed in the high-speed turns of sector two. The Red Bull has a McLaren-like deficit to Mercedes in sector one and a Mercedes-like deficit to McLaren in sector two.
The Red Bull seems to be struggling to get a good front end when on new tyres, but once the rears degrade a little and it finds a balance it's super-quick. In second practice Mark Webber did a 10-lap run on the option tyre that was better than anything McLaren or Mercedes managed.
As ever, the disclaimer is fuel levels and in the past Red Bull has conducted this part of the weekend on lower fuel levels (second stint rather than first) than McLaren.
Mercedes didn't look to be in Melbourne-like trouble with its tyre degradation, team principal Ross Brawn having admitted pre-weekend that his team had been caught on the hop in Australia and would be initiating compromises in the set-up this time around in anticipation.
Rosberg's pace slowed by 1s per lap over just 12 laps on option rubber © LAT
That said, the W03's performance does still appear to drop off significantly: Michael Schumacher and Nico Rosberg did 11 and 12-lap runs respectively on the option tyre and by the end of those stints Schumacher was lapping 0.7s slower than at the beginning, Rosberg over 1s.
Jenson Button was a similar amount slower by the end of his stint - but he'd started it at a much hotter pace than the Mercs. Taking Rosberg's as the faster of the Mercedes stints, Button would be 4s ahead after seven laps. But after a further three laps Rosberg would have clawed half of that deficit back.
Was that just a function of Button's harder earlier pace? Or might the McLaren be looking at a potential degradation problem?
This is a track with a layout, surface and temperature that puts extreme demands on the tyres, so it's quite feasible that teams were pushing hard in order to determine where the optimum combination of early pace and stint duration is - and that we may not therefore see quite the same patterns in the race.
Sebastian Vettel did a five-lap run on the primes at a time the others were on the options and it does appear that the harder tyre may be faster over a stint.
Button's long runs were longer and more consistent than Lewis Hamilton's, but in qualifying simulation Hamilton was finding an impressive 0.2s over his team-mate through the high-speed bends of sector two. He again looks favourite for pole - but can he combine that sort of performance with Button-like tyre conservation?
It was significant that at Melbourne, a track that generates fairly low tyre degradation, Hamilton was in trouble with his tyres by the end of the first stint. Yet when asked about how he'd managed to look after his tyres so well in Australia, Button replied: "People keep saying that but there was nothing to conserve. There was no real tyre deg to worry about there. That won't be the case here."
The Lotus didn't look dialled-in to the high-speed corners of Sepang © LAT
So if Hamilton was disadvantaged to Button around Albert Park by tyre degradation, what might he be around Sepang?
His saviour from another defeat at his team-mate's hands may be whether a Mercedes or two can get between him and Button on the grid. If he can lead away, those Mercs might just protect him from attack by both Button and the Red Bulls. Lots of ifs, though.
Lotus just couldn't get its car dialled into the high-speed sections on Friday - much to the surprise of the opposition. There remains a lot of speed somehow locked in there.
Fernando Alonso put together a good stint on the hard tyres that was ostensibly comparable with the Mercedes', but in qualifying simulation the Ferrari appears to be around 0.7s away.
Of the others, it may be Toro Rosso's turn to head the midfield group and impressively the car was second only to McLaren through the high-speed aero demands of sector two - albeit a distant second. Ferrari probably wasn't figuring on fighting to be the fastest Italian team this year.
Lots of overtaking zones and high tyre degradation - not to mention the always-looming possibility of rain - suggests we're in for an action-packed race. McLaren is the logical favourite, and which of its drivers prevails may depend on where they qualify relative to the Mercs. But don't discount Red Bull either.