IT is now more than a decade since Deep Blue sank its silicon-edged teeth into the throat of the human race's greatest chess champion. Over two matches, the Russian grandmaster Garry Kasparov proved no match for the IBM computer's processing power, his human frailties exposed as he made a series of blunders, including resigning when a draw was still possible.

It shook Kasparov. Afterwards, he said it "left a scar in my memory". But it also shook the world, albeit in a subtle way.

As our champion fell, our relationship with machines changed, too. The vision of computers as our passive servants was fatally compromised. Newsweek declared the match: "The Brain's Last Stand".

In the years that have followed, games that were once the preserve of the human grandmaster have fallen, too. Computers can now beat us at Othello, Scrabble, Monopoly and even bridge. Researchers recently announced the creation of an "artificial intelligence" machine that can never be beaten at draughts. "Chinook" uses 200 computers to run through the 500 billion billion potential draughts positions. Whatever your move, the brute computing power of the machine has seen it, played it and beaten it already.

But the war is not over. This week, the team behind Chinook took on an entirely different challenge: a human versus machine poker match.

The lexicon of poker is the very stuff of human psychology, from "bluff" (kidding an opponent you have a better hand than you do) to "tells" (unintentional twitches which reveal the strength of your hand). Here, you would think the humans would hold the cards. Our gladiators, Ali Eslami and Phil "the Unabomber" Laak - so nicknamed because he wears a hooded sweatshirt and sunglasses - might have felt confident, but the computer representative Polaris (note another war analogy) is no ordinary machine.

Sixteen years in the making at the University of Alberta in Canada, Polaris runs for weeks before a game, creating 10 different "bots" which have their own playing style. It examines an opponent's style. If it spots you playing aggressively or conservatively, then it crushes you.

In the early hours of the morning, after four rounds of Texas hold 'em poker, Polaris folded. The humans had beaten the machine. But only just.

"I literally felt the same feeling that you would have if you beat 500 people in a tournament and won a million dollars," said Laak. "We won, not by a significant amount, and the bots are closing in."

Indeed, it appears it was a human error which probably finally undid the machine. The crucial game had seen its programmers switch to a more sophisticated version of their software. It was ineffective and the humans won that round decisively.

Few, however, doubt that poker will soon go the way of chess and have a computer champion. That would leave only one game where the finest human players consistently beat their silicon-based adversaries. Go, the game considered the world's most ancient, is proving particularly difficult for the robot player. It originated in China, supposedly the invention of an emperor keen to teach his son balance and patience. There is a grid board of 19 lines and two players, one with white stones and the other with black. It relies on intuition over calculation. Processing power will probably not be enough. There are said to be more possible outcomes of a game of Go than there are atoms in the universe.

Even if computers eventually win all our games, does that make them intelligent? Alan Turing, the great British scientist who helped crack the Enigma code and design the first computers, would have enjoyed these battles. His famous Turing Test says that computers can only be considered intelligent if you can have a conversation with them without realising you were talking to a machine. Deep Blue may have been a mean chess player but it was not much of conversationalist.

Others go further. In the late 1940s, Professor Geoffrey Jefferson wrote: "Not until a machine can write a sonnet or compose a concerto because of thoughts and emotions felt, and not by the chance fall of symbols, could we agree that machine equals brain."

It will need computers to do more than win a few hands of poker before the final frontier of artificial intelligence is crossed.