Minato has no way of touching Sasuke, who is protected by Susanoo and preferably covered with Amaterasu flames (in the case Minato intends to touch it in order to warp it away to another location). Well, warping his opponent away can always be an option, but:
a) a Kunai that is placed at another location is counted as prep time before the fight
b) Trying to place a Kunai in a far away location counts as Minato leaving the battlefield and thus giving up
c) Sasuke is not defeated when being brought to another location (it's a matter of opinion whether this counts as a victory. If he tried it on a victim of Konoha, latter would just find back to the village)
Enton gives Sasuke the possibility of turning large areas into flames and spamm multiple Amaterasu missiles, for instance at the directions where the Kunai are placed.
Thus, Sasuke is well protected from Minato and can keep him at bay. Coincidently, he can make use of his Genjutsu and at least the Genjutsu of the Mangekyo Sharingan should be to strong for Minato to handle. If Minato intends to avoid eye contact, he becomes a target for Amaterasu. The likes of Nagato and Zetsu who were sensors felt an ar pressure that was caused by the preparation of Amaterasu. All the further usages are instantly and can't be sensed (Itachi's actual first usage of Amaterasu against Sasuke's Katon then wasn't predicted by Zetsu). Despite this, Itachi also proved a faster usage of the first Amaterasu [
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] and as for Sasuke who is the combatant here, he had another opportunity to prove the instant usage of the first Amaterasu. [
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] Even if the preparation of Amaterasu should take that long for Sasuke's case, after it was done, Amaterasu remains instant and don't need these attributes like the bleeding eye and soaring air pressure for each usage.
