The Olympian is a side-quest which can be started by talking Pigres in the Temple of Apollon, near the city of Mysia in Asia Minor. When taking Syneros with you, the man recognizes him as the Man-Crusher. Pigres' grandfather was supposed to compete with Syneros in pankration in the Olympiads, but Syneros avoided the battle and stole the cup instead.
Pigres wants revenge and thus challenges Syneros to a match of pankration. When Bestia Tabat is also present, he is willing to act as Syneros' champion. He will win the fight, but gets mildly injured or it worsen an already existing wound he has. After the battle has been won, the quest is not over, but all party members gain 20 Experience points.
It's not over yet
When returning to your legion outpost, the contender himself challenges Syneros in a match of pankration. Instead of that, Syneros suggests a battle of riddles, which you and he must answer correctly. With Logos, you can answer the first two question correctly, but in order to answer the third question you need to answer that Alexander didn't pull the knot, which will prompt Syneros to come up with the correct answer himself. The third answer is needed to not fail the quest.