The Red Bull driver had been quickest in Friday's second practice run and this time clocked a time of 1 minute, 24.360 seconds to finish .283 quicker than Ferrari driver Fernando Alonso and .317 clear of Red Bull teammate Mark Webber. Lewis Hamilton was fourth fastest for Mercedes in dry and sunny conditions.
Alonso needs a strong qualifying session in order to pressure Vettel from the outset in Sunday's race.
Alonso has not qualified higher than third all season but will likely need to get on the front row on a Monza track regarded as the quickest in Formula One, and where five of the past six winners have started from pole position.
Although the Spaniard is second overall behind three-time defending champion Vettel, his team has basically given him two races
-- here and Singapore in two weeks' time -- to close the gap before they abandon their hopes and start focusing on developing next year's car.
Monza is a massive race for Ferrari, anyway, and Alonso will want to do well in front of the thousands of flag-waving Italian fans.
But to do that, Ferrari must improve its outright pace because it still lags behind Red Bull, and Vettel is almost impossible to catch if he makes a flying start in good race conditions.
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"I really hope that we can do a good weekend because in front of our people it will be very important. If you want to put the pressure on the guys who are in front of us we need to try to be faster and faster," Ferrari team principal Stefano Domenicali said. "It is not enough to try to be very close to them in case they have an issue."
Lotus driver Romain Grosjean placed a lowly 14th and lamented over race radio that "there is no grip in the car," while Nico Rosberg
-- Hamilton's teammate -- sat in the garage for most of the session as the gearbox was removed from his car due to overheating.
It proved to be a bad session for Force India drivers, with Briton Paul di Resta crashing into a barrier at Parabolica and Adrian Sutil spinning backward across the track after his tires seemed to lock at Ascari.
Press; By JEROME PUGMIRE]
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