Croatia striker Ivica Olic has tested positive for a banned substance at Euro 2004 but is able to continue playing.
Olic has appeared in both of Croatia's Euro 2004 games
Olic, 24, tested for the pain-killing substance methylpresnisolone after the 2-2 draw with France on 17 June, when he was used as a late substitute.
But Uefa's control and disciplinary body ruled the player was not at fault and can play against England on Monday.
The Croatian Football Federation (HNS) has been fined £4,335 for not following the correct anti-doping procedures.
Olic suffered a rib injury during a Euro 2004 warm-up game against Denmark on 5 June and was given a pain-killer which contained methylpresnisolone.
HNS doctor Zoran Bahtijarevic - responsible for anti-doping matters - has received an official warning from Uefa and Boris Nemec, who treated Olic, a reprimand.
Uefa ruled that the two doctors failed to complete and submit the necessary Therapeutic Use Exemption form (TUE) which would have been deemed acceptable.
"Methylpresnisolone is a pain blocker - this is simply a case of the correct people not being informed," said a Uefa spokesman.
"We would have accepted it if we'd been informed - unfortunately we weren't because something went wrong with the administration and there was a mix-up between the Croatian doctor and the doctor treating the player.
"It was the doctor's duty to inform the Croatian FA doctor - and that's why they've been fined and warned rather than the player."
HNS has three days to appeal against the fine.