Shane Long could miss a few weeks with an injury that is suspected to be a broken rib, sustained on Saturday's 3-2 defeat against Crystal Palace.
In that FA Cup fourth-round tie, Long came on as a substitute in the 59th minute but was only in the field for a quarter of an hour before he collided with Palace's Joel Ward and had to be carried off in a stretcher.
An official timetable for his recovery is to be determined but Ronald Koeman believes it will be a few weeks:
"The doctor says maybe its a fracture of one of his ribs."
"We have to wait but we will miss him for sure in the next few weeks."
Long's injury will test Southampton's depth, especially in the forward department. Sadio Mané is still with Senegal at the Africa Cup of Nations, and if they progress to the knockout round, it means he won't be back until after February 1.
Emmanuel Mayuka has returned from Equatorial Guinea after he sustained a groin injury whilst on duty with Zambia. But with only 49 minutes to his name this campaign, it's unlikely Koeman will turn to him in Long's absence.
Other notable absentees for Southampton includes Morgan Schneiderlin, Victor Wanyama, and Toby Alderweireld.