game 1 decklist error

[Jason]

I have a question that almost came up:

It is game 1 in a later round of the tournament. I look at my sideboard before shuffling to make sure I properly de-sideboarded from the previous match. I shuffle my deck and draw my 7 cards; I choose to mulligan. I then pile shuffle my deck and count out 59 cards. (In the real situation, I recounted and then realized I miscounted and I did indeed have my full 60 cards.) My question is: what if I only had 59 cards in the deck (say the other was in the deck box, hidden behind the divider for my deck and sideboard) after I mulliganed but before I drew the 6? I would obviously call the judge, but should I expect a game loss or just a warning? What is the penalty?

[cdr]

Once the deck has been presented, if the deck is illegal, it's a game loss. Once you're to mulligans, the deck has been presented. If you realize your deck is illegal after presenting, you need to call a judge on yourself.

The only situation where the penalty can be downgraded is in the case that you forgot to desideboard before game one, realize it before play has begun (most likely while drawing your hand), and call the judge yourself.