Mike vouches for Worm and takes on responsibility for his debts when they visit KGB's hired hand to ask for more time. They must find $15k in three days. Mike decides to hit the tables at every card game going, and finally before they make their way to a game outside of town for 'State' workers, Mike is up a few grand. Worm lied, and the game is a cops-only house game, although Worm can get a ticket inside. Mike doesn't need or want his friend's help, knowing that Worm will cheat.
Mike is performing well at the table, when Worm shows up after working his way into the game through a cop at the bowling alley. Soon enough Worm is caught cheating, and they are both given the hiding of a lifetme and dumped outside. Worm has a plan to run away from his troubles. Mike knows he must return to the City, and wants to get back to the life he once had.
Mike returns and first asks Knish for the money. Knish is still angry that Mike has never taken his advice, and tells him that he plays to make a living - not for fun. Mike just needs one more chance - and tells the story of how he got the money to play against KGB 9 months earlier -- he won a monster hand against Johnny Chan in Vegas ... and bluffed all the way. Knish is impressed - but still doesn't show him the juice.
Out of options, Mike goes to his college professor, who can only give him $10 grand. Mike cashes it out - and then buys chips at KGB's place. He is going to play KGB for the debt in a heads-up 'winner take all'.
KGB almost has him, but finally Mike has worked out his 'tell' - he breaks an Oreo and then licks it when he has a great hand. Mike folds when normally he would go all in - and tells KGB what he did. KGB is irate and throws his Oreos across the room. With his enemy on tilt, Mike can now win the majority of hands and clears up, taking enough money to pay the debt and still be $5k up.
KGB goads him, that the money was Mike's anyway, and if he was 'man enough' he would play again. Mike accepts the offer. The game continues and they are evenly matched when on the next hand ... Mike flops the nut straight. In response to the heavy-handed repeated showcase of Johnny Chan's famous WSOP winning hand earlier in the movie, he checks it down to the River.
KGB moves all in -- and Mike calls. He wins the hand and all the money. KGB is not about to let him leave - until Mike reasons with his better nature, that he should be allowed to leave as the better player. KGB gives in and leaves the room.
Next day Mike gives Jo a package of money to hand to the professor, and lets her know that he has dropped out of the course. After paying his debts he is still $30k up so does what any Poker player would do after a huge win ... he's off to Vegas!