Except when only two survivors remain in a tournament, poker is seldom played heads-up in home games. One reason is that the social dimension -- pizza, beer, conversation -- is enhanced by a full table of players.

And without a professional dealer, it is an onerous task to shuffle and deal every other hand while trying to play the present one: It can lead to both carpal tunnel syndrome and, worse, the sort of puddin'-headed blunders you'd never make while focusing just on your cards.

Even so, interest in heads-up action expanded in 2001, when Texas banker Andy Beal began a series of individual showdowns against a consortium of pros. Ted Forrest, Jennifer Harman Traniello, Doyle and Todd Brunson, Phil Ivey and a dozen other stars have pooled their resources to be able to face Beal one at a time for stakes as high as $20 million a match. The series will recommence at Wynn Las Vegas next Wednesday.

Many of the millions of Internet players also choose to play two-handed poker. With a computer shuffling and dealing in a flash, the steady intensity of one-on-one, winner-takes-all matches is an appealing alternative to the sometimes glacial pace of nine-handed ring games and tournaments.

Solid play at a full table often involves patiently folding two dozen hands in a row; heads-up, you need to play almost every one. Automatic folds like Q-9 off-suit become raising hands.

No-limit hold 'em against a single opponent is like a street fight, and betting the second-best hand wins a healthy percentage of pots. Few players have much experience at this, however, and the standard primers focus almost exclusively on nine-handed strategy.

But now, Lee Jones, the author of "Winning Low Limit Hold 'Em," and James Kittock, a math professor at Mission College in Santa Clara, have devised what they call the Sit and Go Endgame (SAGE) system. (A sit-and-go is a small tournament, often involving only one table.) They developed it after noticing that most players, including some pros, play far too tightly heads-up.

The system is designed to work when the ratio of the smaller stack to the big blind is less than about 10 to 1 -- for example, when the big blind has climbed to 1,000 chips and one player has fewer than 10,000 remaining.

In this case, the small blind (who acts first) must often choose to either jam (go all-in) or fold. Once the small blind jams, of course, the big blind must choose between calling or folding, and the SAGE system also shows how to optimally defend the big blind.

The system is based on what financial number-crunchers call "equilibrium strategy." If either player deviates from the strategy, his dollar expectation goes down.

Jones and Kittock rank the 169 hold 'em starting hands according to their "power" in heads-up play. A-A is first, of course, and 3-2 off-suit is last. The main departures from full-table values are that big cards become even more valuable, small-suited connectors even less.

The system assigns each card a "power number" based on its rank: A equals 15, K is 13, Q is 12 and J is 11, with 10 and below at face value. You determine the "power index" of your hand with this formula: Double the power number for your higher card, then add the power number of your lower card. If they're a pair, add 22. If they're suited, add 2.

Next, figure the ratio of the shorter stack to the big blind, then use this table to determine whether your power index is strong enough to play the hand. (Jam is small blind; call is big blind.)

Ratio/Jam/Call

1 17 any

2 21 7

3 22 24

4 23 26

5 24 28

6 25 29

7 26 30

Under this system, if your hand's power index is strong enough, you should jam if you're the small blind or call if you're the big blind. For example, say the blinds are 500/1,000, and that after the blinds are posted, the small blind has 5,635 chips and the big blind has 2,865 chips, producing a ratio value of about 3 (that is, the smaller stack is only about three times the size of the big blind).

If the small blind has pocket 3s, his power index is (2 x 3) + 3 + 22 = 31. If the big blind has Js - 4s, his power index is (2 x 11) + 4 + 2 = 28. Because the small blind's power index of 31 is much greater than 22 -- the power index needed to play a hand at that ratio -- he should jam. With the same hand, the big blind should call.

The smaller the ratio, the better the system works. Above 7 to 1, you should simply play good poker -- try to get a physical read on your opponent, decide whether a bluff might work, evaluate your hand and so on. But if you think your opponent is substantially better than you, you can use the SAGE system and be confident you're giving up only a minuscule edge.