J♠9♠ BB vs SB, river on Q♣ 9♦ 6♣ 2♠ A♦, 55 bb

Best play: Bet 40% pot

Why

Hero is the BB in position versus the SB, who acts first on every street; this is a RIVER decision so hands are final. Counting suits: J9 of spades plus board Q (clubs) 9 (diamonds) 6 (clubs) 2 (spades) A (diamonds) gives Hero exactly one pair, a pair of nines with a jack kicker, no flush (only two spades total). The gtoBest small-bet is a thin value/protection sizing: a 40 percent stab gets called by worse pairs (sixes, deuces, busted club and straight draws with showdown value below nines) while folding out almost nothing better. Second pair on a Q-high, A-high runout is too weak to overbet polar, but too strong to simply give up, so a small thin-value bet is the correct middle line.

Key idea

Second pair on the river is often a thin-value bet, not a check or an overbet: size small so worse pairs and busted draws can call, and keep your strongest hands for the polar overbet line.

Common mistake

Players overbet a pair of nines as if it were polar value, which only gets called by better hands and folds out the worse pairs that a small bet would have collected.