Pirelli has warned drivers not to risk keeping full wet tyres on their cars at Sepang while they wait to switch to slicks.
With rain likely to play a role this weekend, the official tyre supplier's chief Paul Hembery said drivers should switch immediately to intermediates as soon as the track is no longer very wet.
Previously, with F1's departed official supplier Bridgestone, drivers could try to make their wet tyres work on a drying track and thereby avoid making an extra pitstop before changing to slicks.
"I don't believe they will be able to do rain (tyres)-to-slick, because the rain tyre is very much a rain tyre and doesn't operate well on drying tracks and will blister very quickly," he is quoted by AP.
"You don't want to be on a dry track with the full wets," warned Hembery.
His comments follow Pirelli's private testing with a Toyota and Pedro de la Rosa last week at Istanbul, where two of the three days of running were wet.