Saints captain Adam Lallana was on crutches, with his knee in a brace, following the 1-0 victory against Reading.
The midfielder was injured in the first-half when Royals midfielder Jay Tabb accidentally tumbled into him.
Lallana was forced off the pitch and was replaced by Gaston Ramirez.
Nigel Adkins revealed after the match that Lallana's knee had been immobilised and that he would be looked at again tomorrow.
“He’s picked up a knee injury,” Adkins confirmed. “As a precaution, as we always do, he’s in a brace and on crutches and we will assess him tomorrow and take him from there.”