Calldown mit JJ als Overpair

Party Poker $25 No Limit Hold'em - 6 players

Opponent is unknown.

SB: $26.69
BB: $25.00
UTG: $27.32
MP: $30.20
CO: $25.00
Hero (BTN): $24.65

Pre Flop: ($0.35) Hero is BTN with J J
UTG raises to $0.75, 2 folds, Hero calls $0.75, 2 folds

We would raise here, but call for setvalue is ok too.

Flop: ($1.85) 4 9 7 (2 players)
UTG bets $1.20, Hero calls $1.20

Our player plays this very passive. A raise would be ok here again.

Turn: ($4.25) 2 (2 players)
UTG bets $2.95, Hero calls $2.95

The same here.

River: ($10.15) 7 (2 players)
UTG checks, Hero bets $4.82, UTG raises to $22.42 all in, Hero folds

The river is the interesting part here. UTG checkraises. The question is why ?
Of course a monster is now possible. Although we think that he is doing this because of the passive play by Hero.
The fold is ok, but we think a call cannot be wrong here.