In hold’em, a player can use one, two or none of his hole cards to create his final hand – if there’s a royal flush on the board, every single player in the pot at the end will receive an equal share of the pot.

But in Omaha you must use two – and only two – of your four hole cards in forming your final five-card poker hand. This rule leads to all kinds of curious situations. In hold’em, you would love to look at your two hole cards and see two Aces. In Omaha, if your four hole cards are the four Aces (or any four of a kind), you essentially have a ‘must fold’ hand (unless, perhaps, you are playing heads-up), because you have a pair of Aces and no way whatsoever to improve them. You can’t make a flush or a straight – you must use two of those Aces – and clearly another Ace can’t hit the board.

Indeed, most hands that contain just three of a kind are completely unplayable, although in a high-only game you might consider trying A♠-A♥-A♦ (a pair of aces and one nut flush draw) from the small blind in a multi-way limp pot, and in high-low you could also play A♠-A♥-A♦ because you would almost certainly hold the only A-2 (you’d also have one nut flush draw, and while your pair of Aces doesn’t add much to your equity, you would be the only player who could hold a pair of Aces).

I vividly remember the first time I played Omaha, in a private game about 25 years ago. The final board showed K♥-Q♣-K♠-Q♥. I had an A-J in my hand, so I had a straight, and I called at the showdown. My opponent, a friend in a friendly game (even though the stakes were £10-£20), held up a lone card, a King, and I tossed my hand towards the muck.

‘What’s your other card, Eddie?’ asked a more experienced player who knew full well it was my first time out. Eddie showed an Ace, meaning he had three Kings with an Ace kicker, and not the full house I was accustomed to that King meaning in hold’em. I protested that I’d held a straight, and because this was a friendly game, Eddie actually gave me half the pot. I’d been ‘entitled’ to all of it, of course, but if you muck your hand in any kind of serious game, what you’re entitled to doesn’t matter.

This is why it’s vitally important to ‘table’ your hand (place all four cards face up on the table, without mucking them) in any situation where you’re not completely sure what you hold. Once you table your hand, other players and the dealer are entitled to help you read it. This assistance often pays dividends, and there’s nothing to be ashamed of. I have seen players at the final table of a World Series of Poker event staring at the same Omaha hand, all trying to figure out what the hand’s owner has!

The 'must two' rule means:

• You cannot ‘play the board.’ You can only play three-fifths of it
• You cannot play a single card from your hand (the ‘Eddie rule,’ as I have come to call it)
• You cannot play three or four cards from your hand
• Just because there are four suited cards on board and multiple players in the hand, it isn’t a ‘lock’ that someone has a flush, because ‘someone’ will have to hold two cards in suit, not just one.

You must get accustomed to thinking of your Omaha hole cards not as individual cards, but as groups of two. With four cards in your hand, you hold six possible two-card combinations. A strong Omaha hand gets equity or value from as many of these six combinations as possible – ideally, significant value from all six.