Southampton chairman Rupert Lowe has issued a warning to Agustin Delgado after the Ecuador striker claimed he wanted to quit the English Premiership club.
Delgado has threatened not to return to Southampton after the World Cup, claiming they did not take his knee injury seriously.
If Delgado fails to return, Southampton could ask Fifa to apply a worldwide ban on the £3.5m striker.
Delgado was allowed to return to South America by Southampton to recover from a knee injury which wrecked his season with the English club.
He told news agency EFE: "I really had a very bad experience in England, I didn't enjoy my days thereat all."
"The people there thought that I didn't want to play, but I was injured.
"My left knee was never right. The doctors failed the diagnosis."
"Southampton officials ended up thinking I didn't want to play because I never bounced back from my knee operation."
Delgado had a first operation in England but, when he failed to recover, had to go under the knife again last February, this time in Ecuador.
He played just 143 minutes of football for Southampton since his signing from Mexican club Necaxa.
But Lowe warned Delgado that he expects him back in England after the World Cup.
Lowe said: "He has a contract with Southampton and if he wants to play football, he has to come back to us.
Delgado surprised Southampton when he played half of Ecuador's friendly against South Africa.
The English Premiership club sought an explanation from the Ecuador football federation after they had allowed Delgado to join up with Ecuador on conditiion that he did not play.
Lowe said: "Apparently he's doing well and we wish him and Ecuador all the best.
"We want him firing on all cylinders and we're looking forward to having back for pre-season training."