Rosberg leads Mercedes one-two in final practice
Mercedes driver Nico Rosberg of Germany returns to the pits during the third practice session of the Formula One Malaysian Grand Prix in Sepang on March 29, 2014 - by Roslan Rahman
Rosberg's time of 1 min 39.008 sec beat Hamilton by two-tenths of a second as the German, who dominated the season-opener in Australia, threw down the gauntlet for the qualifying drive at 4:00 pm (0800 GMT).
Ferrari's Kimi Raikkonen was more than a second off the pace in third and four-time defending world champion Sebastian Vettel, who spent much of the session in the garage, was fourth.
Nico Hulkenberg was fifth fastest for Force India, ahead of Vettel's Red Bull team-mate Daniel Ricciardo and two-time world champion Fernando Alonso in the second Ferrari.
But there were problems for famed but troubled British marque McLaren as both Jenson Button and Kevin Magnussen spent almost the entire session in the garage.
Raikkonen screeched round the final hairpin to go quickest early in the hour-long third practice but he was quickly replaced by Hamilton and then Rosberg as the Mercedes duo locked out the top two places.
Red Bull's Vettel and Ricciardo stayed in the garage until about halfway through the session and when they emerged, they crept up the timesheets without troubling the Mercedes pair.
Rosberg and Hamilton were duelling for the fastest time and, apart from a brief appearance by Raikkonen at the top of the board, the team-mates were on top.
The gremlin-hit Lotus cars both managed a significant number of laps, although Romain Grosjean complained "the rear end is a disaster" after he took a late trip across the gravel.
Several drivers carried stickers reading "Pray for MH370" and the Malay-language version "Doa Untuk MH370" on their helmets in tribute to the 239 presumed killed in a missing Malaysia Airlines passenger jet.
Sunday's race will be preceded by a minute's silence for the tragedy, which has made for a sombre mood at Sepang racetrack and affected ticket sales.