FT 20bb BB Defense Ranges | vs Open by Position [Ajo MTT Vol.5]

Written by: Ajo (X: @AjoPoker)

1. vs UTG Open

UTG opens the tightest range, so BB folds 65.4% of the time.

Call

• A9o+ and broadways lead the calling range

Small 3-bet (5BB)

• Value: AA, AKs
• Bluffs: A4o, K2s, QJo, 23s — hands with ace blockers or that fold cleanly to a 4-bet

3-bet jam

• A2s–A7s, AK, Kxs, QJs dominate
• Under ICM, A and K blockers are weighted heavily, so suited aces sit at the core

Response to UTG's 4-bet (assuming a 5BB resize from UTG)

• Fold: 38.3%
• 4-bet jam: 17.7% (A2s–A8s, AK; small frequency of JJ–KK)

Response to UTG's 3-bet jam

• TT and AQs are indifferent
• Anything below premium is generally a fold

2. vs HJ Open

HJ opens wider than UTG, so BB's fold rate drops to 55.1%.

Call

• Range expands to A7o+, K9o, T9o

Small 3-bet (5BB)

• Value: AA, AKs, AQs, JJ
• Bluffs: one-big-card hands like A2o–A7o, QTo, J3s

3-bet jam

• AQ+, A3o, A4o, A2s–A7s, Kxs, Qxs, JTs, 22–55
• Total jam frequency: 10.1%

Response to a 5BB raise

• Fold: 40.8%
• 4-bet jam: A2s–A7s, AQ+; low frequency of 99–KK
• KK+ mostly calls (a re-jam is also fine, but calling protects the calling range)

Response to a 3-bet jam

• 99 and AJs are indifferent

3. vs BTN Open

BTN opens the widest range, so the fold rate drops further to 43.1%.

Call

• Almost everything except true trash like 27s–29s, 83s

Small 3-bet (5BB)

• Value: AJs+, AK, QQ+
• Bluffs: Axo, 57o, 45o, 39s, etc. (ace blockers or hands with some connectivity)

3-bet jam

• A wide jam range: 22–55, A2o–A5o, A2s–A5s, AJo+, KTo, TT–QQ, Kxs, etc.
• A6s and A7s shift mostly into the calling range (too good to be wasted as a jam)

Response to a 5BB raise

• 4-bet jams led by A2o–A5o, pocket pairs, suited aces

Response to a 3-bet jam

• 77 and ATo are indifferent
• AJo gets a higher EV than 99 thanks to its ace blocker value (a classic ICM-specific outcome)

4. vs SB Open (3BB Raise)

SB heads-ups into BB. Fold rate is 44.5%, and the small 3-bet size is 6BB.

Small 3-bet (6BB)

• Value: QQ+, AJs+, AK
• Bluffs: Kxo, Qxo

3-bet jam

• A wide jam range: Axo, A2s, A3s, 22–44, Kxs, T8s–Q8s, T9o, etc.

Call

• A4s–ATs (BB has only marginal positional disadvantage vs SB, so suited aces stay in the call range to play postflop)

Response to a 6BB raise (SB's effective 4-bet)

• Call frequency: 5.5%
• The dominant line is jam-or-fold

Response to an all-in

• Call with 77+ and A8s+
• Around A9s, folding becomes a viable option

5. vs SB Limp

SB limps in. BB checks at a high rate — 63%.

Check

• Compared to the 3BB-open spot, 88-and-below pocket pairs prefer to check (raising into a limp range gets little fold equity, so taking a cheap flop wins more)

3BB raise (the small attack line)

• The remaining attacking range goes in at this size

All-in

• Hands like A2o, K2o, J2o, A9o — middle-ish offsuit holdings — still jam in equilibrium
• (These are the most common spots where solver and reality diverge — see the warning below)

Response to a 3BB raise (assuming SB raises after limping)

• Fold: 45.2%
• Reasonable calls: roughly 98o–K8o
• 7x hands struggle to call (even against an over-limp range, they don't connect well enough)

Response to all-in

• 66 is indifferent

Summary

The whole point of FT 20bb BB defense is the asymmetry between attacker and defender that ICM creates.

Key takeaways

1. The attacker (Vol. 4) gets a wide jam license — 31.3% from SB, 8.4% from BTN works because of ICM
2. The defender (BB) calls much tighter than ChipEV would suggest — fold rates of 65.4% vs UTG and 55.1% vs HJ are not over-tight
3. Both small 3-bets and 3-bet jams are under-bluffed in real games — equilibrium is the ceiling, not the floor; over-folding is the practical default

Practical operating tips

• When facing a small 3-bet (basically a 4-bet from your perspective), tightening to KK+ for an action is often realistic
• When you do attack from the BB, lead with ace-blockers (Axs / Axo); pocket pairs and suited connectors are de-emphasized under ICM

FT 20bb Open Ranges — Position-by-Position ICM Guide [Ajo MTT Vol.4]

The companion piece — opener-side ranges across UTG / UTG+1 / +2 / LJ / HJ / CO / BTN / SB.

📖 10 min ★★★★☆

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