Scotland midfielder Scott McTominay has travelled to Boston separately from the rest of his team-mates after missing Thursday’s training session because of an upset stomach.
The Napoli player, who has been the Scots’ leading man in recent campaigns, made the journey with a doctor in what is believed to be a precautionary measure.
Steve Clarke’s side get their first World Cup in 28 years under way when they face Haiti on Saturday evening (Sunday 02:00 BST) at Boston Stadium in Foxborough.
They will also face Morocco and Brazil in the group stage.
McTominay, who has scored 15 goals across 70 caps, found the net in Scotland’s convincing 4-0 win over Bolivia on Saturday.
Scotland fans, who have been flooding to Boston in huge numbers, will be anxious for an update from Clarke who is due to address the media on Friday.
Speaking at Thursday’s media conference, fellow midfielder Kenny McLean said of the situation: “Hopefully that doesn’t spread. Fingers crossed Scott will be fine. I’m sure he will be.
“I don’t need to speak too much on him, everyone knows how big he is.
“It’s a team effort and always will be, but when you have special, special players like that you want them to be available. I’m sure he will be.”