Difference in Kyuubi states?

Naruto many times uses Kyuubi chakra, but the way he uses it is he calls upon the fox to give him that power.

The first time that Naruto uses Kyuubi (against Haku) seems different. He didn't call on Kyuubi's power, instead Kyuubi seemed to partially possess Naruto. Naruto was completely transformed, rage consumed him.

My question is, when Naruto looses his senses with rage from Kyuubi, is that more powerful than just calling on Kyuubi's chakra?

That would boost the idea that Haku was a very high level ninja, espcially when even Zabuza and Kakashi admitted it.

So in the upcoming fight between Sasuke and Naruto, do you think Naruto will pull out the "possessed by Kyuubi" transformation?

the haku transformation is indeed stronger than his own. the rage when he thought his friend was dead was like an oppurtunity for kyuubi to break loose, thats why he needed to learn how to call it so he could control kyuubi better. when he calls kyuubi's chakra himself its no where near the power when kyuubi wants to get out.