Source: Leading unsupported aces against a suit contract – part 1, Bulletin February 2006 ACBL
When I lecture on opening leads against a suit contract I inevitably get the question about leading unsupported aces. Many players feel that leading an ace is a good idea because (a) it may be the right lead and (b) if it is the wrong lead, you
may be able look at dummy and figure out what is better.
I am on record, along with just about every good player that I know as being strongly against ace banging. One of the hardest thing to prove is that leading unsupported aces is a terrible way to make a living.
Few things are more annoying than to lead some other suit and watch declarer get rid of two losers and then later find out that if you had led your ace, you would have taken two more tricks. This can happen.
What is more likely to happen (trust me on this) is that banging down your ace will give up one or more tricks later in the play.
Now, reflecting that leading an ace can be effective some of the time, lets see when that might be. Note, by the way that I will not discuss leads against slams. That is a different case Don’t e-mail me about leading an ace against a slam.
Here is an assortment of hands where you are on lead. You are South in each of them. Specifically do you lead your ace or not/ If not, what do you lead? For each question, decide what your reasons are. Reasons count for more than guesses.
1) No one vulnerable. North dealer
A 10 6 
5 2 
J 9 7 6 3 
Q 8 2
| West | North | East | South |
| 1 |
Pass | 2 |
|
| Dbl | Pass | 3 |
The End |
2)
1) No one vulnerable. North dealer
A 10 K 4 Q J 10 7 4 2 10 7 3
| West | North | East | South |
| 2 |
3 |
3 |
|
| 4 |
The End |
3)
1) No one vulnerable. West dealer
Q 6 5 3 A 7 3 J 10 9 7 7 3
| West | North | East | South |
| 1 |
1 |
1 |
2 |
| Pass | Pass | 2 |
The End |
4)
1) East-West vulnerable. West dealer
A 10 7 3 Q J 10 6 J 8 3 10 9
| West | North | East | South |
| 1 |
Pass | 2 |
Pass |
| 3 |
Pass | 3 |
Pass |
| 3 |
Pass | 4 |
Pass |
| 5 |
The End |
Answers
1) The gut reaction is to lead the A. Partner bid them, did he not? If you recall all the times you have opened 1 with five to the jack or five or the queen-jack, however you will recognize that there is an excellent chance that your partner does not have the king. Further on this auction, West has said that he has support for the unbid suits. He promises short spades. If you lead the A you are likely to see a singleton spade in dummy. Declarer will now be able to ruff a spade or two with eases. Much better to lead a trump. If your side can lead two or three rounds of trumps, declarer may not get any ruffs at all.
2) Lead the Q. When your side has bid a suit and the opponents declare, leading a doubleton ace is a normal thought. Who knows, you might take two tricks and a ruff; too. The reason you do not lead the A here is that you do not rate to have a ruff coming. Even if you get one, it is with a natural trump trick. I know that I have opened a lot of weak two bids with suits like Q-J-9-6-4-3 and if North has that type of suit, leading the ace will set up the king for the opponents, wherever it is. You have a nice diamond sequence to lead from, so that is the clear choice.
3. Do not lead the A. If you have an attractive alternative, it should routinely get the nod over the ace. Note that if you do not lead the A, your partner will suspect you have it. He knows that leading hearts would be attractive to you. Not leading them hints that you have the ace. Why else would you not lead that suit?
4. This is a rare case for leading an ace. This situation is extra rare because your partner did not bid spades. The reason you should lead the A is that your opponents chose not to play in no trump. They bid all the suits, some more than once, and no one ever showed interest in notrump. Usually 3NT is the target, but on this hand the opponents bid to five of a minor, which generally takes a back seat to to 3NT. The A gets the top score of 10 in this poll,the Q gets only a two.