One of the biggest mistakes that players make in tournament poker involves side pots. For those who may not know, a side pot is created when a short-stacked player is all in and two or more active players (players with chips remaining) continue to play on the side.

The old adage used to be that players competing in a side pot should check it down unless one of them improved his hand. This was considered to be a common courtesy of sorts. It was done to increase the chance of eliminating the all-in player — two against one is better than one against one — thus bringing everyone else a step closer to victory.

However, that line of thought is not only outdated, but it will cost you valuable opportunities to pick up chips.

As an example, let's look at a hand from a European Poker Tour event in Prague last December — a tournament that attracted 1,044 players. A year earlier, American Stephen Graner defeated a record field of 1,107 players to win the Prague main event, claiming a prize of 969,000 euros. Graner returned in 2015 to defend his title, but he ran into trouble in Level 6, with blinds at 200-400 plus an ante of 50.

It happened when Jochum Weenink opened for 900 from middle position and Mustafa Biz called. When action reached a short-stacked Graner in the cutoff seat, he three-bet to 3,000, leaving himself just 2,175 behind.

Action folded back around to Weenink, who four-bet to 5,400, and then Biz came in with a five-bet to 12,500. Graner didn't seem thrilled, but called off the rest of his stack nonetheless. Weenink put in the additional chips to create a side pot, and the two active players saw a flop of 8h Qs 6s.

Weenink checked, Biz bet 10,500, and Weenink got out of the way. Graner showed Kc Qc for top pair, but he was behind the Ac Ad of Biz.

An As on the turn left Graner drawing dead, and he wished the table luck before the 6d on the river made his elimination official.

In this hand there were numerous factors that made checking it down a terrible idea. First, there was nearly as much in the side pot as in the main pot, meaning there was simply too much at stake not to compete. Second, Biz held a premium hand, one that was more than likely good unless Weenink had flopped a set. Biz needed to protect it, which meant placing a bet. There was no reason to give Weenink a free card to win. Doing so would have been reckless and unwise.

You may wonder if you should check it down if the side pot is only small one, or if you don't have a quality hand. When side pots are involved, every situation is different.

Just make sure you're always thinking of ways to win, rather than just automatically checking it down and hoping that you have the best hand.