LAUSANNE - FIFA is on an ambitious mission to make sure that for the first time every player who takes part in the World Cup has a drug test and carries a 'biological passport'.
Football's governing body wants to impose the passport - already used in cycling and athletics - that will follow a player throughout his career, giving details of blood and urine tests.
Since March, a team of FIFA doctors and nurses have been carrying out random blood and urine tests at internationals and team training camps.
Lionel Messi's Argentina and France were visited last week at their camps to prepare for the tournament, according to media reports.
Brazilian star Neymar, Italian captain Gianluigi Buffon and Spain's Andres Iniesta were among those who gave samples at last year's Confederations Cup.
Chelsea, Barcelona, Santos and Monterrey stars were tested during international club competitions over the past 18 months.
Players can expect a tap on the shoulder right from the first matches of the World Cup which starts June 12.
"We can test anybody, anytime, anywhere, any amount of times," said Jiri Dvorak, FIFA's chief medical officer in a recent interview.
So far nothing alarming has turned up, according to Dvorak. "The hematological parameters are normal," he said.
FIFA is building up a biological passport on all players.
It has taken at least two test samples from most players while some have given up to four.
So far teams have made the doping investigators welcome. "They understand what we are doing and they consider that kind of examination as part of their professional life," said Dvorak.
The FIFA tests look for discrepancies in haemoglobins and red cells that could indicate EPO doping or other banned efforts to boost endurance. These kinds of tests are already used in cycling and athletics.
Football's governing body also checks hormone levels and for anabolic steroids in the urine.