小盲位河牌圈第四次加注（彩虹牌面）（SB River 4-Bet Rainbow）

Term Composition

• SB: Small Blind, the position to the immediate left of the dealer, required to post half a big blind preflop.
• River: The betting round after the fifth community card is dealt.
• 4-Bet: Preflop, this typically refers to the third raise (beyond the blinds). Postflop, the raise count in a betting round starts from the existing bets in the pot. Here, "4-Bet" means the fourth raise in that round (i.e., raising after three raises have already occurred), representing a very deep-line action.
• Rainbow: A rainbow board, where three (or four) community cards on the flop or final board are all of different suits, reducing the possibility of a flush draw.

Typical Scenario

In No-Limit Texas Hold'em, the Small Blind is usually in a disadvantageous position (acting first postflop). When the river shows a rainbow board, there is no flush draw and the board is relatively dry. In this situation, an SB 4-bet typically indicates a very strong made hand (e.g., the nut straight, trips or better), aiming to maximize value or discourage opponent bluffs. Since a 4-bet on the river is extremely rare, this action can also be a bluff, but it is generally not recommended for frequent use in low-stakes games.

Strategic Significance

• Value: SB makes a 4-bet with an extremely strong hand to force the opponent to pay more chips.
• Bluff: After correctly reading the opponent's range, the SB can exploit the rainbow board's lack of draws to represent a strong hand and force the opponent to fold medium-strength holdings.
• Risk: A river 4-bet easily telegraphs hand strength, and if the opponent holds the nuts, they may 5-bet shove.

Note

This term is not an official standard poker term, but rather a colloquial description of a specific action by players. In actual games, players more often use phrases like "fourth raise on the river" or simply describe the bet size.