The first matches of Euro 2012 will be played later today, but the tournament is already seeing signs of its worst fears coming to the surface — racist fans openly taunting black players.

To give you an idea of how important the European Championships are to soccer fans on the continent more than 25,000 people came out to Stadion Miejski in Krakow, Poland, on Friday just to watch the Netherlands national team practice. Unfortunately, a sizable group of fans greeted the team's black players with monkey chants and other jeers. UEFA and other top officials tried to make excuses for the fans' unruly behavior, claiming they were simply protesting seeing an enemy team in their stadium or the fact that Krakow was not made an official host city for the tournament. But Dutch captain Mark van Bommel wasn't having it, saying "You need to open your ears. If you did hear it, and don't want to hear it, that is even worse."

The Daily Mail also reports that a gang of about 50 masked "thugs" attacked foreign fans speaking English and Russian outside pub in Lodz, in a more traditional case of hooliganism. 

Threats of ugly racial taunts and possible violence have hung over the tournament for weeks, fueled in part by a BBC television special that focused on the openly racist and anti-Semitic behavior by some Polish and Ukrainian soccer fans. (The English team will practice in Krakow today.) Some prominent black players have already expressed concerns, with Italian star Mario Balotelli saying he will quit any match if he is threatened and UEFA promising yellow cards to anyone who does storm off the field. Should a similar incident happen during a live game, being broadcast to the world, it would put a serious blemish on the whole sport.

The tournament officially opens later on Friday, with co-host country Poland kicking things off against Greece at noon Eastern time.