Croatia forward Nikola Kalinic has been sent home from the World Cup after he refused to come on as a substitute during the 2-0 defeat of Nigeria.
The 30-year-old cannot be replaced, meaning Croatia will have to make do with only 22 players for the rest of the tournament.
AC Milan’s Kalinic said he had a back injury, having complained of the same problem in the friendly loss to Brazil.
Coach Zlatko Dalic said: “I need my players fit and ready to play.”
Kalinic, who played for Blackburn Rovers between 2009 and 2011 and has scored 15 goals in 41 appearances for Croatia, was starting his fourth international in a row on the bench.
“During the Nigeria encounter, Kalinic was warming up and was supposed to come on in the second half,” said Dalic.
“However, he then stated that he wasn’t ready to come on due to a back issue.
“The same thing happened during the Brazil friendly in England, as well as before the practice session on Sunday.
“I have calmly accepted that and since I need my players fit and ready to play, I have made this decision.”
The striker spent last season on loan at Milan from Fiorentina, scoring six goals in 41 appearances, before making the move permanent this summer.
Croatia’s winning start came as Oghenekaro Etebo’s own goal and a Luka Modric penalty decided a poor Group D match in Kaliningrad.
They face Argentina on Thursday (19:00 BST) and finish their Group D campaign against Iceland on Tuesday 26 June (19:00 BST).