Your opening lead in a hand of bridge tells your partner quite a lot about what you have in the suit you’re leading. The information you relay in the opening lead, in turn, helps your partner plan the defense.
When you defend a notrump contract, your side and your opponent (the declarer) both try to accomplish the same things:
You both want to establish tricks in strong suits. With the KQJ10, for example, you both want to drive out the ace and establish three tricks.
You both want to take tricks with small cards in long suits by relentlessly playing the suit until your opponents run out of cards in the suit. After you get rid of their cards, your remaining cards in that suit are winning tricks.
Before you make your opening lead, you have to listen to the bidding. During the bidding, the opponents frequently tell you how strong they are and in which suits they do and don’t have strength. The clearer the picture you get of both their hands, the more likely you are to find the most lethal lead.
You also need to pick the right card in the suit that you lead. Nine times out of ten, you’ll lead either your fourth highest card or the top of a sequence in your longest suit. Because your goal is to establish tricks, and because tricks come from long suits, your best shot is usually to lead from your longest suit.
The hand in this figure gives you a chance to kick off with your longest suit.
The bidding has gone as follows:
| South | West (You) | North | East (Your Partner) |
| 1♠ | Pass | 2♣ | Pass |
| 2NT | Pass | 3NT | Pass |
| Pass | Pass |
You must make the opening lead, and you have plenty of information from the bidding to help you decide which card to lead. The opponents have bid spades and clubs. Because you don’t want to lead suits that the opponents have bid, lead a diamond or a heart, whichever suit is longer. In this case, you lead the ♥2, your fourth highest heart.
If your opponents bid both of your long suits, so you have only two or three cards in the unbid suits, you may try a short-suit lead hoping you lead partner’s strongest suit. If the opponents bid all four suits, you’re on your own! You may treat the auction as if they had bid none of the suits, and fall back on old faithful, your longest suit.