[The Funky Llama]

You have to call here imo simply because there are so many hands in his range that either flopped or turned a straight draw: 24s, 25s, 45, 47, 57, 78, 79, 89, 9J, 9Q, JQ. Most of these hands are probably in this guys sb openraising range. Then on top of this, he could have flopped a flush draw -- this adds a lot of combinations because he is opening most suited hands from the sb (although there are a bunch of lags who would never play a flush draw this passively so we could discount these hands against such players). It isn't like the board is 227Kr. Villain knows that his hand looks a lot like Ax to you so it is not unlikely that he will bluff at this particular river getting the attractive price of 5:1. Then there is also the remote possibility that he has something like 22 or 43s and is bluffing despite having some showdown value.

I would probably call this river getting as little as 2:1 or 3:1. Getting 6:1 its an easy call imo.