Budapest - Heavy rainfall delayed the start of the qualifying session for the Hungarian Grand Prix by 20 minutes on Saturday.
Championship leader Nico Rosberg of Mercedes was fastest in the morning practice session, which was completed about 45 minutes before rain drenched the Hungaroring circuit.
Rosberg, who also posted the fastest time in Friday's second practice, edged Max Verstappen of Red Bull by just two thousandths of a second. Verstappen's teammate Daniel Ricciardo was third fastest, 0.465 seconds adrift.
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Two-time defending champion Lewis Hamilton, who has recovered from a crash early in Friday's second practice, was fourth fastest, 0.508 seconds behind his team mate Rosberg.
Hamilton reported "an overheating car" with a radio communication with his team midway through the session, but Mercedes said the temperature problem was restricted to the car's seat, which was quickly changed.
Ferrari's Kimi Raikkonen and last year's winner Sebastian Vettel were next.
Before of the last practice, FIA, motorsport's governing body, reaffirmed its commitment to "zero tolerance" for cars going off the track.
Charlie Whiting, FIA's Formula One race director, confirmed in a note to the teams that, during qualifying, "lap times achieved by leaving the track will be deleted."
During the race, drivers leaving the track three times at turns 4 and 11 where electronic sensors have been installed, will be shown a black and white warning flag, with one more infraction likely leading to a drive-through penalty, Whiting said.
The penalties, however, would not be applied if FIA found that the driver left the track "for reasons beyond his control."
The issue of going wide on the tracks controversially surfaced again at the British Grand Prix two weeks ago, when several drivers, including Hamilton, had qualifying laps deleted by race stewards.
Rosberg leads the championship with 168 points halfway through the 21-race season, one point ahead of Hamilton.
Pablo Gorondi contributed to this report.