UEFA have vowed to catch out drug cheats in football by introducing out-of-competition testing for all 16 teams who qualify for next summer's European Championships.
European football's governing body can now check for the presence of newly-discovered steroid tetrahydrogestrinone - THG - in players' samples, following advice from the World Anti-Doping Agency, and players will be randomly subjected to testing.
UEFA chief executive Gerhard Aigner promised that next summer's finals in Portugal would offer no home for the minority of footballers who may be tempted to use performance-enhancing drugs.
THG, which has been found in the systems of several leading track and field athletes, has now been added to the list of banned substances on the UEFA list, on the advice of WADA.
The testing by medical staff belonging to European football's governing body will be in addition to any already put in place by national associations.
There was also confirmation from UEFA that players would be tested at this weekend's play-off matches - and after matches at the finals themselves.
Aigner said: "UEFA are taking new steps to ensure that we have the widest possible coverage of testing before Euro 2004 and at the tournament itself.
"This is completely in line with the overall increase in testing that we have introduced in our club competitions and that were announced after the UEFA executive meeting in September of this year.
"The message is clear - we will not tolerate those who cheat using banned substances and will act decisively if anyone is found doing so."
Of the 396 player tests carried out by UEFA during the 2002-03 season, there was only positive test.