[dickiegera]

Why when holding Axxx opposite Q1098

is is wrong to play Ace first and then lead to the Q10?

I know that one should either lead Q or 10 for a finesse or
lead small to the Q10 first.

If you need 4 tricks you must lead Q trying to drop J

Mathematically Why?

[dustinst22]

 dickiegera, on 2011-March-30, 16:37, said:

Why when holding Axxx opposite Q1098

is is wrong to play Ace first and then lead to the Q10?

I know that one should either lead Q or 10 for a finesse or
lead small to the Q10 first.

If you need 4 tricks you must lead Q trying to drop J

Mathematically Why?

Needing all 4, cashing the ace you are obv praying K is singleton. And of course leading Q you hope to pin the jack singleton. However, there's also a small chance East will misdefend on the Q lead and not cover the first round.

[manudude03]

Without going into the precise numbers, when you run the T, you make 3 tricks when either of the honours is onside (you run the T incase it breaks 5-0 and you can change tactics). If you cash the ace and lead towards QT, if opp follows low, you have a guess and so you lose half of the time it is split honours.

If you need 4 tricks, it is a crapshoot as far as I know. (stiff K behind QT, or stiff J in front of)

[manudude03]

 dustinst22, on 2011-March-30, 17:10, said:

Needing all 4, cashing the ace you are obv praying K is singleton. And of course leading Q you hope to pin the jack singleton. However, there's also a small chance East will misread the situation and not cover on your Q lead, and now you may pin a jack doubleton.

You still don't pick up jack doubleton in that case.

[dustinst22]

 manudude03, on 2011-March-30, 17:15, said:

You still don't pick up jack doubleton in that case.

Ah true. However it seems you are at least allowing for some misdefense from East in the second case (leading the Q). Maybe he covers the 2nd round. Whereas cashing the ace, you don't allow for that.

[pooltuna]

LHO RHO fin Q, fin T Play A,lead x Fin win Play A win
KJ765 - W L 1 0
J765 K W W 1 1
K765 J W W 1 1
KJ65 7 W L 1 0
KJ75 6 W L 1 0
KJ76 5 W L 1 0
765 KJ L W 0 1
J65 K7 W W 1 1
J75 K6 W W 1 1
J76 K5 W W 1 1
K65 J7 W W 1 1
K75 J6 W W 1 1
K76 J5 W W 1 1
KJ5 76 W L 1 0
KJ6 75 W L 1 0
KJ7 65 W L 1 0
65 KJ7 L W 0 1
75 KJ6 L W 0 1
76 KJ5 L W 0 1
J5 K76 W W 1 1
J6 K75 W W 1 1
J7 K65 W W 1 1
K5 J76 W L 1 0
K6 J75 W L 1 0
K7 J65 W L 1 0
KJ 765 W W 1 1
5 KJ76 L L 0 0
6 KJ75 L L 0 0
7 KJ65 L L 0 0
J K765 W W 1 1
K J765 W W 1 1
- KJ765 L W 0 1
24 19

[chasetb]

pooltuna has the right idea. Here are the results based on suitplay, setting North as A432 and South as QT98. Playing the Ace must be inferior, because it lists only two lines - Lead 10/9/8 planning on finessing, and Lead Q, planning on finessing. On a few of the hands, I made comments when it's likely to differ if you play the Ace immediately:

West East 10 Q Prob.
KJxxx - 3 3 1.96% *Ace loses
KJxx x 3 3 8.48% *Ace loses
KJx xx 3 3 10.17% *Ace loses
KJ xxx 3 3 3.93%
Kxxx J 3 4 2.83%
Kxx Jx 3 3 10.17%
Kx Jxx 3 3 10.17% *Ace loses if you guess incorrectly, so I'll call it -5.085%
K Jxxx 4 3 2.83%
Jxxx K 3 3 2.83% *Ace wins 4
Jxx Kx 3 3 10.17%
Jx Kxx 3 3 10.17%
J Kxxx 3 3 2.83%
xxx KJ 2 2 3.39% *Ace wins 3
xx KJx 2 2 10.17%
x KJxx 2 2 8.48%
- KJxxx 3 2 1.96% *Ace will get 3 tricks

Leading the 10/9/8 overall wins by a score of 77.96% - 76.00% when aiming for 3 tricks (both are even in making 4 tricks), gaining on singleton K onside as well as when KJxxx is behind the Axxx. Leading the Q only wins when the singleton J is offsides. By my math, the Ace will gain 3 tricks about 56.195%, making it a CLEAR #3. The Ace will gain you 4 tricks on 5.66% compared to 2.83% for the other 2; that doesn't make up for it clearly getting PWNED!

This post has been edited by chasetb: 2011-March-30, 19:09

[pooltuna]

you might want to look at Ax opposite QT9876 for an interesting result IMS