It looks like Raikkonen was better in a couple of the extremely slow corners, Mirabeau in particular.
Heading into Mirabeau Raikkonen was a couple of car lengths behind Vettel; Vettel's front wheels are on the front edge of the pedestrian crossing as seen from Raikkonen's camera.
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Heading toward the hairpin, Raikkonen is possibly in front of Vettel.
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That one corner earned Raikkonen pole. Throughout the remainder of the lap Vettel, Bottas and Raikkonen were approximately matched, although Raikkonen appeared to generate better traction out of the slow corners, with Vettel carrying more entry speed into turn 1.
It should be an interesting race, although I anticipate Vettel will win.