Just stop right there bro, you have got to be one of the biggest Itachi fanboys on all of NB, this is why people consider him overrated. First, Itachi hit him with Amaterasu when Kabuto(who was controlling Nagato btw....) didn't realize he broke free. He then proceeded to Shinra Tensei the flames off his body, he could of done this the first second it hit him if he wanted to.... Second,
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he used Azura path to grow extra arms to detain Bee, he didn't get his real arms chopped off and thus would still be able to use Chibaku Tensei. Third, Itachi STILL asks for them to use their strongest attacks on gravity ball, no one knows if Itachi would of destroyed it by himself, most likely not because he still asked for help. The truth is, Nagato had a major handicap for that fight, he's crippled, he's being controlled by someone unfamiliar with his powers, and he's fighting three of the strongest ninja in the entire series. Who knows how the fight would of gone down if Nagato had his full attention solely on Itachi.