Michael's first fight was against Thaor. The Berserker was curious to find out how much stronger Michael had grown after advancing to Tier-3.
Thaor was still at the Peak of Tier-2, and there was just a thin line separating him from reaching Tier-3 as well. All he had to do was cross the small hurdle and he would be a Tier-3 Awakened. However, that small gap indicated a major difference in strength. Every breakthrough to the next Tier led to a massive surge of strength.
Michael ought to be much stronger than Thaor, however Thaor was in possession of a Unique Constitution. It didn't count as a Soultrait, allowing him to use Crimson Aura in a Soulless Fight.
