If we think that partner has led a singleton and we gain the lead, then we return the suit to give him a ruff (providing he has trumps, i.e. not after trumps were drawn), partner's next problem is going to be how to get us into play again. The Lavinthal convention works nicely in this and similar situtation as well.
At this instant we can signal which suit to lead after ruffing. If we play low then we request the lower, if we play high, we request the higher ranking of the remaining two suits (disregarding trumps)!
Against 4♠ partner leads the heart deuce:
We take the trick with our Ace, declarer following with a small. Now we can see that the lead was a singleton, because only honours are missing! (Holding KQ, partner would have lead the King, from doubleton honour, the honour!)
Now giving partner the ruff is not the only thing that matters, but also that he leads a diamond after the ruff, so we can make him ruff again, beating the contract. Thus, after the ♥A we lead the ♥9 asking for a diamond back. If we had the Ace of clubs, we would have given him the ruff with the heart three, asking for a club.
Generally a high card asks for the higher suit and a low card asks for the lower suit. Having a lot of cards in a suit we can discard a middle card, if we cannot decide, which suit is better, so we give back the decision to our partner.
- We also use Lavinthal convention in all situations, when the opening lead is obviously wrong, and we would like to point P in the right direction!
- Many pairs also play Lavinthal convention in 1st discard situations, in order to discard an unnecessary card from the hand, and lead direct the partner as soon as possible.
- The Lavinthal convention is efficient and is used world-wide for lead directing in ruffing situations!