Hextall broke a 3-3 tie 6:23 into the third with a shot from behind the net that deflected in. O'Sullivan made it 5-3 shortly after and later scored his second with the man advantage.
Andrew Cogliano and Kyle Palmieri each had a goal and an assist for the Ducks, who pulled within 5-4 on Nate Guenin's power-play tally midway through the third.
League MVP Corey Perry did not suit up for the Ducks as both teams went with younger lineups.
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