You're missing the point by harping on the politics thing. It shows that in many areas, Panther is Doom's superior intellectually. And it shows that Doom respects his intellect. And even outside the whole political thing, Doom couldn't find Panther inside Doom's own castle. Inside your own home. AND you're the smartest person in the world? That proves that Panther is inside Doom's head.
As for head to head combat - I've always believed that Iron Man is a better combatant than Doom. We saw what Panther did to Iron Man. He'll do it to Doom, and given Doom's arrogance and constant underestimating, he'll have Doom retreating and scratching his head in no time.
Panther.