Celtic captain Scott Brown will be sidelined for up to six weeks after undergoing surgery on an abductor problem during the international break.
Brown has been struggling with the thigh muscle problem for over a month and it was decided an operation was the only solution for the Scotland midfielder.
The 27-year-old had also been troubled by a pelvic injury for much of the season and the Scottish champions have been forced to nurse him through a campaign which has seen him miss 13 matches.
Hoops boss Neil Lennon, speaking ahead of Sunday's Scottish Premier League clash at St Mirren, confirmed that Brown wouldn't be back for at least a month and also revealed Norwegian defender Thomas Rogne has suffered a hamstring strain.
"Scott Brown had surgery in the break and so he is looking at a month, four to six weeks," Lennon said on Friday.
"Thomas Rogne has a hamstring strain and he will out for two to three weeks."