[kgr]

..from RP site...
AJT9x
  -
xxxx

It is best to take two finesses; however, if this is inconvenient (or risks a ruff if this is your trump suit), it is almost as good to cash the ace first.
Comparing both against each other:
Two finesses looses if East has KQ : 6.78%
Cash the ace first looses if West has KQx(x) : 12.43% + 4.78%

=> Two finesses is much (10%) better then cashing A first or am I missing something?

[Fluffy]

I didn't know the difference was so huge.

the only small thing you might be overseeing is that sometimes you cannot pick 4-0 anyway since you need some ruffs yourself, or you lose controls or lack entries ETC.

[ceeb]

I think you're right to be surprised if people say "about equal" when the difference is 10%.

In partial defense of "people" though, the difference seems less extreme if you comparing winning %. The double finesse wins 76%, ace first 66%. Sometimes 76% vs 66% is less significant than, say 17% vs 7% (and in fact your 17% and 7% calculations didn't represent either winning or losing cases, but are just calculation made after eliminating the majority of cases in which the lines are equivalent).

[BillHiggin]

It seems to all be in the definition of "almost" and "huge".
The double finesse loses 1 trick 76% of the time and the ace first loses 1 trick 66% of the time (just for matmat, the difference is 10.4348% ). But losing the first finesse and conceding a ruff (assuming this suit is trumps) may be a risk. If that is a likely risk or entries (or need to ruff twice in short hand) is a problem, then 66% is "almost" as good. Without those considerations, the difference is "huge".

[inquiry]

Perhaps the discussion was (should) have been about AJT9xx (six) opposite xxxx. With this holding bang the ace and finessee are truely about the same. In fact, if memory serves me correctly, playing the ACE is first is slightly better as KQ offside is slighly more likely than KQx onsides.

[jdonn]

inquiry, on Jul 12 2008, 09:45 AM, said:

Perhaps the discussion was (should) have been about AJT9xx (six) opposite xxxx. With this holding bang the ace and finessee are truely about the same. In fact, if memory serves me correctly, playing the ACE is first is slightly better as KQ offside is slighly more likely than KQx onsides.

I doubt that after taking one finesse, someone would then finesse into the only other missing card in the suit.

[skjaeran]

jdonn, on Jul 12 2008, 06:12 PM, said:

inquiry, on Jul 12 2008, 09:45 AM, said:

Perhaps the discussion was (should) have been about AJT9xx (six) opposite xxxx. With this  holding bang the ace and finessee are truely about the same. In fact, if memory serves me correctly, playing the ACE is first is slightly better as KQ offside is slighly more likely than KQx onsides.

I doubt that after taking one finesse, someone would then finesse into the only other missing card in the suit.

Don't be too sure about that.
I've experienced a declarer playing the trump queen from hand, finessing when my partner showed out, and losing to my bare king!

[andy_h]

skaeran, on Jul 13 2008, 03:49 AM, said:

jdonn, on Jul 12 2008, 06:12 PM, said:

inquiry, on Jul 12 2008, 09:45 AM, said:

Perhaps the discussion was (should) have been about AJT9xx (six) opposite xxxx. With this  holding bang the ace and finessee are truely about the same. In fact, if memory serves me correctly, playing the ACE is first is slightly better as KQ offside is slighly more likely than KQx onsides.

I doubt that after taking one finesse, someone would then finesse into the only other missing card in the suit.

Don't be too sure about that.
I've experienced a declarer playing the trump queen from hand, finessing when my partner showed out, and losing to my bare king!

I've also experienced a declarer with an 11 card fit missing the Q decided to make a first round hook, losing to the bare Q. ahh..good old yahoo days...

[ArtK78]

The most remarkable play of this type ever reported to me was declarer, in a grand slam in spades, gets the lead of a heart. Declarer's side has an 11 card HEART fit missing the King. Declarer finessed at trick one, losing to the bare K offside.

Of course, if the K was onside, RHO would have ruffed.

[jdonn]

I have had my 62 doubleton of trumps finessed on the first round by an old lady, as partner showed out. But I guess it's not as bad as the other plays. Her's won, after all.