Marquez had earlier been fastest in third practice, having also led Friday's second practice session, and proved to be unbeatable over one lap around the 2.7-mile circuit.
The Spaniard's opening gambit, a 1m28.731s, left him three tenths of a second clear of the rest.
Though his opposition improved, Marquez held the same advantage at the end of the session after going faster himself with a 1m28.364s.
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Iannone and Lorenzo's matching times came right at the death, as the pair crossed the line in tandem.
Two-time champion Lorenzo, however, was fuming after the session after Iannone rode in his slipstream to match his best lap and sandwiched his Ducati between Marquez and the Yamaha rider on the front row.
"This time Andrea benefited a lot from my wheel," said Lorenzo. "I did my best."
Iannone admitted what had happened and even thanked Lorenzo.
"Without Jorge for sure, yes, I improve -- but not at this big step," the Italian said.
Lorenzo's starting position is still a boost to his championship hopes, however, with team-mate and championship leader Valentino Rossi four spots behind.
The Italian's seventh place was an accurate reflection of his pace so far this weekend relative to Lorenzo and leaves him with work to do to in Sunday's race to get on terms with his rival.
He was beaten by the second Honda of Dani Pedrosa in fourth and the impressive duo of Cal Crutchlow and Maverick Vinales in fifth and sixth respectively, the pair continuing the strong form they have shown since Friday.
Both Espargaros came through the earlier Q1 session and Suzuki's Aleix ended the session with the bragging rights after securing eighth on the grid, narrowly ahead of brother Pol.
Australian Jack Miller will start his home event from 15th after missing out on advancing to the second session.
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