Fourth-best leads are a standard defensive agreement on the opening lead and on subsequent leads. They are made from suits that are four cards or longer, and do not contain an honor sequence. Examples:
- KT53 - lead the 3.
- J9652 - lead the 5.
- T7542 - lead the 4.
Examples of when NOT to use fourth-best leads:
- AT53 - lead the ace against a suit contract. Against no-trumps, the proper lead would still be the 3.
- KQ93 - lead the king against a suit contract (i.e. the top of any honor sequence). Against no-trumps, the proper lead would still be the 3.
- KJT5 - lead the jack (i.e. the top card of an interior honor sequence) against both suit and no-trump contracts.
- 9872 - suit sequences headed by the 98 (or lower) require partnership discussion. Many players would lead the 9 instead of the 2.
Fourth-best leads are used in conjunction with the Rule of 11
. This mathematical formula is used by the opening leader's partner to count how many higher cards declarer has in the suit.