We all know that Itachi was basically throwing Kakashi and Kurenai around like nothing. Asuma was no help. Itachi was freaking out three of Konoha's top Jonin.
But what about Kakashi and Guy? They're a really powerful duo together. Very good teamwork. Guy is more battle adept than what we've seen of Kurenai and Asuma, so if it were Kakashi and Guy, would both of them have been able to beat Itachi?
Itachi's at his prime. Kakashi and Guy are at their ablities right before the 4SWW. Guy is restricted from his 8th Gate. They have any knowledge they'd have of each other at the beginning of the 4SWW