Performance gap between medium and soft tyres drops as track temperatures fall during the evening race.
Top 6 of today's free practice result were claimed by Mercedes-powered teams.
Transcript of the Friday press conference organised by the FIA for the 2014 Malaysian Grand Prix.
Kamui Kobayashi got into Q2 and Marcus Ericsson only went through Q1.
The agreement, stipulates that each team will devote one day per year exclusively to testing the latest products and developments from Pirelli.
Whiting said the next set of rules will require nose "symmetry".
After Red Bull's catastrophic opening test at Jerez last week, even F1 backmarkers Marussia and Caterham are currently ahead of the formerly-dominant world champions' game.
Vettel managed just 11 laps with the RB10 over his two days, and now hands over to teammate Daniel Ricciardo.
Testing begins at Jerez today.
Caterham F1 Team and Caterham Racing have confirmed Alexander Rossi for 2014.
End of the F1 road for Charles Pic for now.