The Finn, a former winner for Ferrari in China, jumped to the top of the order with a one minute 36.896 second lap in Friday’s second practice session, beating German team mate Vettel by a margin of 0.109 seconds.
Championship leader Nico Rosberg was third for Mercedes, 0.237 seconds off Raikkonen’s benchmark.
Rosberg’s team mate and reigning world champion Lewis Hamilton, who heads into Saturday’s qualifying session with a five-place grid penalty for a change of gearbox, was fourth, 0.433 seconds adrift.
Rosberg had set the fastest time ahead of Hamilton in Friday morning’s interrupted opening session in which the Ferrari duo were only third and fifth.
But the Maranello-based squad turned the tables on their German rivals in the afternoon with their runs on the fastest, red-walled, super-soft compound tyre.
Friday afternoon’s practice session was only the second time this season that a Mercedes has not ended a session on top.
The German team has won 34 of the last 40 races and started the last eight on pole.
Rosberg, who leads the standings by 17 points from Hamilton, heads into Sunday’s race gunning for a sixth-straight win.
The Briton, meanwhile, is aiming to complete a hat-trick of Chinese Grand Prix victories, even if the highest he can start the race from is sixth.
Red Bull’s Daniel Ricciardo ended the day fifth, the Australian, fourth in the morning, setting a time 1.247 seconds adrift.
McLaren driver Fernando Alonso, cleared by doctors to compete in Sunday’s race after a final round of medical tests following the morning session, was eleventh.
The Spaniard, forced to miss the last race in Bahrain due to injuries sustained in an accident last month in Australia, completed a total of 42 laps over the entire day.
Friday afternoon’s running was uneventful compared to the morning’s action.
The opening 90-minutes were headlined by two red-flag stoppages as Williams driver Felipe Massa and Renault’s Kevin Magnussen both suffered high-speed left-rear tyre failures while running on the soft-compound rubber.
Following an investigation, the sport’s tyre supplier Pirelli confirmed none of the failures were tyre-related with a separate technical issue responsible.
The Mercedes pair also reported problems in the morning.
Rosberg limped home near the end of the session with engine issues while Hamilton, struggling with “locking” problems, spun twice at turn 11.
