Despite his isolation, Naruto trains hard to be a ninja, dreaming of one day reaching the ultimate rank of Hokage.
In this case, Naruto remembers Neji’s earlier fight with Hinata and how he stopped her Chakra flow, preventing her from using jutsus.
Unfortunately, most everyone is convinced Naruto has no chance against Neji, which is why Naruto receives special training in the leadup to the competition.
Then there’s Neji Hyuga, who Naruto fights in one-on-one combat as part of his ninja exams to reach the rank of Chunin.