First of all, the Emei martial arts and the Nine-Yin True Classics that Zhou Zhiruo had learned before were originally one yin and one yang, which belonged to Xiangke's martial arts. Even if she is highly qualified, she is self-contradictory in learning and can't exert the greatest effect at all.
Secondly, Zhou Zhiruo is a woman after all. Compared with Zhang Wuji, who was very strong in her early twenties, she is definitely a big difference in strength.
The last and most important point is a data analysis when two people compete. At that time, Zhou Zhiruo's "Jiuyin Zhenjing" was only a part of Jiuyin Bones Claw, and his practice time was very short. Her internal skills are shallow, and she collapsed in such a short time. Don't say all the Nine Yin Scriptures, even the Nine Yin Bones and Claws can only be counted as 30% to 40%. In this way, she has been deadlocked with Zhang Wuji for dozens of rounds.
On the other hand, Zhang Wuji, although young, practiced Jiuyang magic for a short time, but his qualification is a little higher than that of Zhou Zhiruo, and his internal strength is much higher than that of Zhou Zhiruo. Based on the Wudang internal family law transferred by Gan Kun and Zhang Sanfeng, Zhang Wuji practiced Jiuyang magic for a short time, but at least it has reached the top level, which should not be much different from the maximum skill of Jiuyang magic, at least it can reach more than 80%.
So, so Zhang Wuji played dozens of rounds with 80% of Jiuyang siddhi and Zhou Zhiruo practiced about 30% of Jiuyin Bones Claw, and with the previous two points, it was obvious that the two kinds of martial arts were up and down.