Scenario: It's down to one prize each, your turn with 10HP left, and you're poisoned. You attack and KO your opponent to draw your last prize. But you take poison damage and would be KO'd now too. Do you win or does it go to Sudden Death?
You win, you must complete the rest of the combat sequence, but then if you win BEFORE the end of the turn, you win, period. Poison doesn't happen until after the end of your turn.
Source: WotC Chat (2000-10-05)