Source: www.abf.com.au Newsletters
DOUBLETON LEADS
Leading from honours against suit contracts was considered the norm 30 years ago, but with the rise of the internet and BBO it became obvious that aggressive leads conceded too many tricks. A 2012 book by David Bird and Taf Anthias, Winning Suit Contract Leads, has changed the way players lead and defend. The book analyses dozens of hands on lead with computer as simulation 5000 times each situation, then plays out the hand to see which leads work best.
The main conclusion is that it is losing tactics to lead from honours, especially aces and kings, and good tactics to lead singletons and doubletons. Which of these would you prefer to hold:
65 opposite QJ72 or Q6 opposite J752
65 opposite KQ72 or Q6 opposite K752
Clearly the first holding in both layouts is a better chance to take more tricks. In the first example, by leading towards the QJ you will set up a trick when the ace and king are split. In the second example, you will set up two tricks when the ace is in front of the KQ. This sort of situation is a. frequent winner for doubleton leads. Players consider a weak doubleton in a strong notrump opening to be a serious flaw, but really a suit like xx opposite AQJxx could well take five tricks but Qx opposite AJxxx should never take five tricks. Apart from the obvious chance of scoring a ruff or leading towards partner’s strong honour holding, doubleton leads work well in other weird and wonderful ways. This trump suit illustrates how doubleton leads can create an extra trick in the trump suit:
In a large field most pairs played 4
from the strong hand, but four tables wandered into 5
. Let’s say South leads 
K and continues to A and East plays a third diamond. West can ruff this with Q and when North overrufs with K the defence magically has a trump trick with 1084. This next deal is from a recent event at the NSWBA (New South Wales Bridge Association). EW were in the bidding with their diamonds but the final contract was 4 by South. It seems declarer will have no problems losing just a heart, a diamond and a club. Try it yourself and see if you can see if you can defeat 4:
After the round and we were looking at the hand record, and only Sartaj Hans could find the winning defence. The doubleton spade is the only winning lead and to prevent the imminent ruff’, declarer must draw trumps. West ducks the first round of trumps but rises I A on the second trump and now plays A and another diamond, which declarer ruffs. This is then the position:
Stuck in hand, there is no way to avoid losing two more tricks. If declarer draws the last trump, the defence can take +A and a diamond, and if declarer crosses to a spade to ruff the last diamond, then the defence scores a spade ruff when declarer tries to cross back to dummy to draw West’s last trump. The doubleton lead is a winner by threatening a ruff !