Well, I think because Jiraiya was mentor of the 4th Hokage (and was one the three Sanni) that's why Itachi was careful with Jiraiya perhaps as he had seen only Orochimaru and even he is sharpest caliber from the three Sanni when speak skill wise.<br/><br/>Anycase we have to consider Orochimaru was not figthing Naruto, but nine tails. Which is<strong><em>strongest</em></strong>of all tailed beasts. And tailed beasts themselves each and every one (even one tailed) has tremendous powers.