Republic of Ireland boss Mick McCarthy could be without first-choice central defensive pairing Shane Duffy and Richard Keogh for next month's Euro 2020 double-header against Georgia and Switzerland.
Brighton's Duffy is expected to be sidelined for several weeks by a calf injury picked up during Wednesday evening's 3-1 Carabao Cup defeat by Aston Villa.
Manager Graham Potter, speaking at his pre-match press conference ahead of Saturday's Premier League trip to Chelsea, said: "Shane is going for a scan, so we will see the extent of that. It looks like it is going to be weeks rather than days with him. It's a calf."
Derby defender Keogh will certainly miss the two games after being ruled out for much of the rest of the season with a knee injury suffered in a car accident.
A club statement released by the Rams on Thursday afternoon said: "As a club, we cannot, and do not, condone the actions of a small group of players on Tuesday evening.
"The players were out as part of a scheduled team-building dinner with staff and while the majority of them acted responsibly and left at around 8pm and were not involved, a small group, including the team captain Richard Keogh, continued drinking into the night.
"They should have known when to stop and also ignored the opportunity to be driven home using cars laid on by the club, and chose to stay out.
"As a result of an alcohol-related incident, Richard Keogh has sustained a serious knee injury that will prevent him from playing until the end of the season."
Ireland play the Georgians in Tbilisi on October 12 and the Swiss in Geneva three days later, and the results will have a significant say in whether or not they make it out of Group D.
McCarthy's men currently top the group by two points ahead of Denmark and three clear of Switzerland, who have played a game fewer.
Duffy, 27, and 33-year-old Keogh have started all five competitive games under their new manager and would almost certainly have been paired together again next month.
Sheffield United's John Egan and Kevin Long of Burnley got the nod in last month's friendly victory over Bulgaria, while Newcastle defender Ciaran Clark, who has made only once appearance for his club so far this season, is an experienced option.