CO 75bb Defense
CO 75bb Defense
The range and strategy used by the player in the Cutoff position when defending against an open-raise with an effective stack of approximately 75 big blinds.
Overview
CO 75bb Defense refers to the optimal calling and 3-betting ranges for the Cutoff (CO) position when facing a raise from an earlier position (typically Under the Gun or Middle Position) with an effective stack size of 75 big blinds. At this stack depth, post-flop playability and implied odds are significant considerations, as 75bb is deep enough to allow for multi-street maneuvering but not so deep that speculative hands gain excessive value.
Strategic Considerations
Position and Stack Depth
- The CO is a late position but not the final pre-flop aggressor (the Button and Blinds act after). Therefore, the CO must balance value, protection, and deception.
- At 75bb, the SPR (Stack-to-Pot Ratio) after a standard 3-bet or call is moderate (~13-15 for 3-bet pots, ~25-30 for single-raised pots). This favors hands that can make strong top pairs or draws.
Defense Ranges
Typical CO defense ranges at 75bb against a 2.5-3bb open from early position include:
- Calling range: Broadways (AJs+, KQo, QJs), suited connectors (98s+), small to medium pairs (22-99), and some suited aces (A2s-A5s). Hands like AJo and KQo may be called or 3-bet depending on opponent tendencies.
- 3-betting range: Value hands (TT+, AQo+, AJs+) and some bluffs (AXs, suited connectors like 76s, 87s). The ratio of value to bluffs adjusts based on opponent fold-to-3-bet.
Adjustments
- Against tight openers: Narrow the calling range, increase 3-bet bluff frequency with high-card removal (e.g., A5s).
- Against loose openers: Widen calling range with playable suited hands, reduce 3-bet bluffing as opponents call wider.
- Post-flop: Hands that flop well (e.g., suited connectors with backdoor draws) are more valuable at 75bb due to implied odds. Avoid marginal calls with dominated hands (e.g., KJo vs a tight UTG range).
Common Mistakes
- Over-defending with weak offsuit broadways (QJo, JTo) that are easily dominated.
- Calling too many speculative hands (e.g., 32s) that need deep stacks (>100bb) to be profitable.
- Failing to 3-bet enough with value hands, allowing the opener to realize equity cheaply.
Related Concepts
- Position: The CO has positional disadvantage post-flop compared to the Button, but advantage over the Blinds.
- Stack Depth: 75bb is a medium stack; adjustments are needed for shorter (<50bb) or deeper (>100bb) stacks.
- 3-bet Defense: The CO must also defend against 3-bets from the Button or Blinds, often by calling or 4-betting with a polarized range.
In summary, CO 75bb Defense requires a balanced approach that leverages position and stack depth to maximize value while avoiding costly dominated confrontations.