Ryu didn't slow down or relax after he entered the Legacy World. He didn't believe that the Dao Sovereign had locked onto him for long enough to tell where his exact location was, but he wasn't taking any chances.
Primus had managed to sense him without Ryu even being aware of what was happening. Of course, Primus was also the stronger of the two, him being a half step into the Dao God Realm, and there was also likely some factor to play in the fact that while the Karma between himself and the Chaotic Space Dao Sovereign was strong, it couldn't be stronger than what he held with his great grandfather, but even so, Ryu had already learned not to underestimate Dao Sovereigns once today, he wouldn't make that mistake again so casually.
