What happens when a player knocks and misreads their hand?

This hand recently came up:

I announced a knock but mistakenly included a card as deadwood that could have been played. If the card (6c) had been included with my 7c8c9c trick my opponent would have been able to play his 4c5c and undercut me. I obviously made a mistake and should have included the 6c. Should I be forced to correctly play the 6c and allow him to play his cards, or should my announced play stand?

  • Did you have more deadwood than just the 6c? If not you would have been gin.
    – LeppyR64
    Commented Oct 4, 2015 at 23:01

2 Answers 2


You are not forced to "correctly" play the 6c, actually sometimes (rarely) it is an expert move to discard a card that is part of a meld.

For example, assume you knock while holding the run {3c,4c,5c,6c} and you know that your opponent is holding the 7c and 8c. by discarding the 6c you deny your opponent a layoff of 15 points.

From RummyTalk, which is one of the best online Gin-Rummy strategy guides:

sometimes it is wise to discard from a run when you are knocking. This can prevent lay-offs that could cost you dearly. There may be times when your opponent has nine melded cards and is holding up the one card that can be layed-off with your hand. In that case, breaking up the run will cause him to have to hold onto that card eliminating the underknock.


This answer assumes Pagat rules. As pointed out by a commentor, other rules sources may disagree.

The announced play is illegal, and a legal play should be made instead. Here is what the rules from Pagat.com have to say about Knocking:

... This is done by discarding one card face down on the discard pile and exposing your whole hand, arranging it as far as possible into sets (groups of equal cards) and runs (sequences). ...

According to that rule, you must arrange the cards into sets and runs as far as possible. Since it is possible to include 6c in a run of 7c8c9c, you must.

The Gin Rummy Association developed a set of tournament rules to supplement the regular rules. If you were playing in a tournament and had already recorded the score for the hand, then you would be stuck with your mistake, per rule 17:

Once a count has been AGREED TO BY THE PLAYERS AND RECORDED BY THE SCORE KEEPER, the hand stands.

  • 2
    One rules set says to arrange as far as possible, but all the others I've looked at mention nothing of the sort. I personally prefer the option to make a suboptimal hand if you can tell what your opponent is trying to play based on what they think you're doing.
    – Samthere
    Commented Oct 6, 2015 at 10:24
  • 1
    @Samthere I think you are right. I chose to use Pagat as my source, but I failed to cross reference other sources. I will leave this answer here because even if it is wrong, it may be useful to someone.
    – Rainbolt
    Commented Oct 6, 2015 at 13:09
  • The answer is wrong. You can arrange your hand as you like.
    – Cohensius
    Commented Jul 11, 2019 at 20:37
  • @Cohensius As explained in the answer, that's not true if you are playing by Pagat rules. Once you knock, you must rearrange your hand as far as possible into sets and runs. That is, by definition, not "as you like".
    – Rainbolt
    Commented Jul 19, 2019 at 14:08

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