He must hide outside, because just after ten minutes, Hidden Pavilion Master would arrive. Ye Feng was very much interested in having a look at him, because he actually wanted to see how the card of Cai Shao was.
Since the opposite party was his opponent now, that was the reason why Ye Feng must know himself and his opponent! Now, both sides were in the dark, hence, the more he would know the opposite party, the more advantage he would get over him.