People seem to be underestimating Hiruzen's prowess in genjutsu. He was a master in all forms, ninjutsu, taijutsu, and genjutsu, just saying.
Another thing we saw Tobirama and Hashirama get defeated by a weakened Hiruzen (I mean weakened by age because he had low chakra) so in Prime you have to admit that Hiruzen would be a beast, granted I don't believe we saw all his abilities before his death. Another thing even with lower reserves of chakra Hiruzen was still able to preform strong techniques left and right showing powerful chakra control...now for me I'd say they'd both die but the fact is Itachi and Hiruzen were cool wit each other so they ain't gonna fight each other