8♠7♠ CO vs BB, turn on J♣ 8♦ 5♠ Q♠, 85 bb

Best play: Check

Why

The Q♠ turn is an overcard that connects with the BB's capped check-back range while also bringing a spade backdoor live, so neither side gains a clear nut advantage and the action checks to hero in position. Hero holds 8♠7♠: middle pair (a pair of eights) with a spade flush draw and a thin gutshot to T — a marginal made hand with backup outs, not a hand that wants to bloat the pot. Since it was checked to hero IP, checking back controls the pot, denies villain a chance to check‑raise a weak pair into a fold, and keeps the bluff‑catch / showdown line open while the draw can still improve.

Key idea

With a marginal made pair plus a draw in position, checking back keeps the pot small and the bluff‑catch open instead of turning a showdown hand into a bluff.

Common mistake

Turning middle pair with a backdoor flush draw into a raise — you fold out everything you beat and only get called by better, so you bloat the pot as the underdog.