Daryl Janmaat punched wall and broke two fingers during Newcastle's stormy post-game inquest
The defender signalled that he wanted to come off after slipping in the build-up to Southampton's second goal.
United manager Rafa Benitez revealed after Saturday's 3-1 loss than Janmaat had felt his groin.
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Hide AdBenitez said: "He said that he had a problem with his groin, so we have to wait and see.”
However, Janmaat also left the St Mary's Stadium with two suspected broken fingers, having punched a wall during a stormy post-game inquest.
The result left the club second-bottom of the Premier League, and six points adrift of safety, with six games left to play.
Janmaat's injuries are being assessed ahead of Saturday's home game against Swansea City.