I don't think there was any chance of Naruto breaking the seal. At that point the seal was still very strong and he wasn't yet able to even access the Kyuubi's chakra so again I
chalk that up to the series just beginning. Anyway this seal thing isn't very clear from what I saw when the third used it I don't know how it could've been used to seal the Kyuubi in Naruto although it was originally the fourth's technique so I think only he would know.

At one point it was said that the seal was in the process of breaking, then it was said that it wasn't because the seal was designed so that Naruto could gain access to the Kyuubi's chakra, then it was said that the seal was incorporating the kyuubi's chakra with Naruto's.

It was also said that Naruto could release the Kyuubi at anytime by just willing the seal to break which I don't think is true because we have seen him get desperate many times and literally beg the kyuubi for chakra yet the seal didn't break and designing the seal so that it would break just because the host got angry and wanted some extra chakra is foolish.

Now I know some idiot is going to say that the seal is breaking because how else would Naruto have been able to go one tail but it isn't. As we've seen from the very beginning Naruto has been able to access more and more of the kyuubi's chakra over time but that is simply due to his chakra capacity increasing as he grows older and uses the Kyuubi's chakra more not because the seal is breaking but because it is designed to allow Naruto to use the Kyuubi chakra.

What jounin level opponents has Naruo defeated?

The thing with Kiba and Lee is that they are far more skilled than Naruto is and they have more jutsu at their disposal. The only person Lee fought was Gaara and we all know he really stood no chance, and Kiba only fought the sound ninjas and none of the leaf ninjas involved in that mission really 'won' anything. The only two people anyone could make a case for is Choji and Neji and they by all rights should have been dead.

Yeah I don’t think I’m biased. Biased would mean that I’m prejudiced and predisposed to act in a particular way or have a certain opinion and I’m not. My opinions and conclusions are all the result of what I’ve seen and are supported by evidence therefore I’m not bias. “Naruto is a classic close combat idiot,” who is overemotional and only knows a total of three jutsu, whose only strategy is to charge at his opponents and he didn’t even graduate the academy. That is all fact.