Ha! The viz translation said something entirely different. "You can't beat Sasuke just by being strong. What's inside him....."
This indicates that he has the necessary strength to go toe to toe with Sasuke with SM alone. However, he knows he can't beat Sasuke's ideals.
I looked up the viz clear up thread and got this....
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Here's the link to the page if you don't believe me.
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P.S. Sasuke never admits that anyone's better than him openly. It's always within thought. If his thoughts aren't revealed, then we can't know what he's actually thinking.