Sometimes there's so much money in the pot that you have to call. Most of these times, the correct play is to fold and save that last bet to buy somebody dinner.

Playing a game of \$20-40 limit hold 'em, action folded to me in the small blind, and I had As 10c. I raised, and the big blind called.

I got a great flop of 10h 7s 3c, fired out a bet and was called. The turn was the Js. I bet, and he called. The river was the 5d, I bet, and he raised.

Really? The 5 is what made you? What was he representing? Would he call the turn with 4-6? Would he call preflop with 10-5, 7-5 or 3-5? It's possible he had 5-5. Or he was bluffing. Or slow-playing some goofy two pair. But what could he be bluffing with?

Whatever. There was \$320 in the pot, it was only \$40 to call and I had a good hand, so why not call?

That's the thought process most players have in this kind of a spot, and it's a mistake. The only thought that matters when they raise you on the river, especially in limit poker, is deciding whether they are bluffing. In this spot, we were being offered a hefty price of 8-1 on our money. This means that if he is bluffing more often than one in nine times, or 11.1 percent of the time, then the play is to call. If we deduce that our opponent is bluffing fewer than one in 10 times, then the play is to fold.

Your verdict on whether your opponent is bluffing is based on history, individual hand dynamics and physical tells. Tells are a science, and based on how your opponent behaves, you can turn calls into folds and vice versa. The hand dynamics encompass what you think he may have, what he thinks you have, and what he thinks you think he has. Often this stops at level one; people simply play their hand. The gathering of information from all hands prior will help you figure out what level your opponent is on, how he plays and what his tells are.

As the pot size changes, the numbers skew. Our pot odds grow or shrink, indicating that we should call more or less often. However, people assume that nobody is folding for one more bet in a big pot, so they generally don't bluff at it. And conversely, they assume they can steal small pots easier and bluff at them more.

In this spot, I had no reason to believe that my opponent was bluffing. My read on him was that he was strong. He had no history of bluffing, nor did he view me as bluffable. He played at level one all night: I'd never seen him do anything questionable, and he was rumored to be a calling station.

I finally shrugged and threw my cards into the muck. He turned up 7-5 offsuit and said, "Good fold."

One last thought: If you can identify thinking players who are willing to make big folds on the end, try raising the river on them every once in a while. They'll fold big hands if they don't think you're bluffing. But if they ever think there's any chance you're bluffing, they'll usually call because the pot is so big.

Bryan Devonshire is a professional poker player from Las Vegas. Known as "Devo" on the tournament circuit, he has amassed more than \$2 million in career earnings.