Underpair in Poker: A Pocket Pair Below the Board
An underpair is a pocket pair below every card on the board: 3♠3♦ on K♥ 9♣ 4♠. It beats hands with no pair (56% to 69% of the pot in the table below) and smaller pairs, but against top pair it keeps only 8.8%. It improves to a set 8.4% of the time by the river. In practice, it checks or bets small and gives up under pressure.
Compute an underpair
3♠3♦ on K♥ 9♣ 4♠: what it beats
Equity with the turn and river to come:
| Opponent | What it holds | 3♠3♦'s equity |
|---|---|---|
| 2♣2♥ | a smaller pair | 90.3% |
| 8♦7♦ | no pair, two cards above the threes | 69.4% |
| T♦8♦ | no pair, two cards above the threes | 68.9% |
| A♠Q♠ | two overcards to the threes | 68.3% |
| A♥T♥ | two overcards to the threes | 67.6% |
| Q♣J♣ | two overcards and a gutshot | 55.7% |
| K♦J♦ | top pair | 8.8% |
Against two cards above the threes, the underpair is a favorite but not by much: they keep 31% to 32%, and a gutshot added on top brings them to 44%. Against a king, it is drawing to two outs.
How to play it
- Check or bet small, and keep the pot small. A big bet folds the hands it beats and is called by the kings it loses to; a small one can still get value from smaller pairs and charge overcards.
- Call small bets from wide ranges. Facing a small bet from a player who bets many hands without a pair, the underpair often has the equity to continue: see pot odds.
- Let go against pressure. A big bet or a second barrel usually holds a pair or better; with two outs, the underpair cannot chase.
- Do not count on the set. 8.4% by the river is too little to pay a big price for; set mining works before the flop, with deep stacks: see implied odds.
Keep going
- One step up, the pair just below the top card: second pair.
- The other side, a pocket pair above the board: how to play overpairs.
- What equity means: poker equity.
Sources
- Equities enumerated exactly over every turn and river; set count: 91 of the 1,081 turn and river pairs.