'The most interesting questions from visitors to the Dutch sister site (Bridgevaria.nl)'. 

Dear Ed & Peter,

Why am I not allowed to underlead an ace against a trump contract?

Marlène de Haas

Answer Ed Hoogenkamp (South)

Dear Marlène,

First I want to make it clear that you can do as you like, so if you want to underlead an ace no one can stop you. Therefore I will rephrase your question somewhat: why do bridge teachers and experts advise against underleading an ace at the opening trick against a trump contract?

It simply is too risky. If declarer has the king, you allow him to make it and the question is whether you will still score your ace later on, since declarer may ruff (the ultimate nightmare: the bare king in dummy!). In notrump this risk does not exist.
Leading the ace when you don't have the king yourself is ill-advised as well, since this will often set up one or more tricks for the declarer.
In short: against a trump contract you will usually not lead a suit to trick one in which you have the ace but not the king. Later, after you have seen dummy, things are different since you can see what's going on.

Peter will explain in which situations you can consider underleading an ace to trick one (Norwegians love to do so, I've been told).

Regards from Barcelona

Answer Peter van der Linden (North)

Dear Marlène,

Ed is right but needs many words to explain himself. That's southern temperament for you (you should see him talk: everything moves, even his toes gesture!).
What he tries to say: rules like 'don't underlead an ace against a trump contract', 'cover an honour', 'third hand high', 'second hand low', 'eight ever, nine never' et cetera, are not really rules but advices. They are meant to give some guidance to beginners. The more experience a bridge player gains, the more he will recognise situations in which he must ignore these advices.

To underlead an ace at the opening trick against a trump contract indeed often costs a trick, see Ed's examples. Often too because in doing so you put partner on the wrong track:

		♥	J 8 6
♥	A 9 5 2			♥	K 10 7 4
		♥	Q 3

Spades are trumps, South is declarer. If you, West, lead the ♥2, declarer will duck in dummy and partner will insert the ♥10! You can't blame him for that, since he will expect the ♥A behind him and the ♥Q with you (or, if you and partner lead third/fifth best, inserting the ♥10 is correct as well, since you may have led from ♥9x2). If he were to play the ♥K in that (assumed) layout, declarer could later set up dummy's ♥J, on which he could pitch a loser.
In the actual layout however, declarer will lose only one heart instead of two when East plays the ♥10 (in notrump, where underleading an ace is common, it isn't a problem that East plays the ♥10: declarer will always make a heart trick; EW's goal is to set up the suit and they will succeed, no matter what heart East plays).

For once Ed is right with his standard final remark about Norwegians: indeed I like to audaciously underlead an ace.
Experts (I don't see myself as one) do likewise sometimes, especially when dummy is expected to be strong and balanced.
Sometimes they even underlead an ace against a slam! Just click here for an example.
Another example from practice:

N/All		♠	K 9 2
		♥	A J 9 7 4
		♦	K 6
		♣	K 10 3
♠	7 6			♠	5
♥	8 6 5 3			♥	Q 2
♦	Q 9 4 2			♦	J 10 8 7 3
♣	A 7 2			♣	Q 9 6 5 4
		♠	A Q J 10 8 4 3
		♥	K 10
		♦	A 5
		♣	J 8

¹ at least five-card suit
² shows a diamond control, denies a club control (!)
³ Blackwood
⁴ two aces

West had paid attention to the bidding. From his hand it was clear the distribution in hearts and trumps was very favourable to NS. Therefore, if EW were to defeat this slam, they would probably have to take the first two tricks. West had noted that South had denied a club control and still North had headed for the slam. North had to have a club control therefore. The chance of it being the bare ♣K was very small indeed (and if so, it was very unlikely the contract could be defeated at all). So West led a small club, hoping NS had the ♣J but not the ♣Q. His hopes were fulfilled.
South, unsuspecting of West's cunning, ducked in dummy. Applause for West, since on any lead but a small club declarer would easily have made his slam. Right...?
Not so fast: it actually happened that East inserted the... ♣9! So the slam was made after all! Do you see what I mean with my earlier 'putting partner on the wrong track'?
Of course East should have inserted the ♣Q. Firstly because to underlead a jack against a slam (by playing the ♣9 he hoped West had the ♣J!) is very rarely winning. Secondly: East too should have paid attention to the bidding, he too should have heard that South had no club control. So East should have known what West was doing...

Of course it gets even better if both West and South are known ace players and know each other. A few years ago a similar occasion turned up in a top level match. Internationals and leading Dutch players Bauke Muller and Huub Bertens were West and South respectively.
Muller deduced from the bidding that to underlead his ♣A was his only chance to kill the slam and so he did.
Bertens knew that Muller knew that the bidding demanded the opening lead of a small club lead, whether Muller had the ♣Q or the ♣A. The moment Muller's small club hit the table and dummy went down Bertens told his partner to play the ♣K. Not because he knew it would win the trick (he couldn't tell: as I said Muller had to lead a small club, whatever his club holding was) but as a matter of prestige! Oh well, boys will be boys...

Aside: in the layout above the NS bidding is absolutely correct and that is exactly what led (OK: could have led) to their defeat! If South, as so many players would have done, immediately after 3♠ would have asked for aces and bid 6♠ next, West couldn't have found that diabolical opening lead; probably he would have chosen a diamond lead.
Yes, bridge isn't always fair (but it's always fun!) since sloppy bidding sometimes pays (but correct bidding pays more often).

To conclude with: to underlead an ace in a trump contract at trick one is very dangerous and only very occasionally winning. Experts do it extremely rarely and only with a very good reason.
Bridge teachers tell you not to do it ('Don't try this at home') but I think that's patronising...

Regards from Orkanger

Reaction Ed Hoogenkamp (South)

Indeed it's impressive how few words Peter needs to make his point....