Hamilton secures pole position at Hungarian GP
Hamilton set a pace of 1 minute 20.953 seconds in Saturday's qualifying session, .413 seconds better than Grosjean, who achieved his first front-row start of the season.
World championship leader Fernando Alonso of Ferrari was sixth, behind McLaren's Jenson Button and fifth-place Lotus driver Kimi Raikkonen.
Alonso has 154 points after 10 of 20 races, 34 ahead of Mark Webber, who will start only from the 11th place on the grid on Sunday. Vettel is 44 behind the Ferrari driver.
Sunday's race at the Hungaroring leads into a monthlong summer break before the Belgian Grand Prix on September 2.