However, coach Mike Marsh is optimistic about Reina's chances ahead of the Premier League encounter at St Mary's.
"He's coming along nicely. He's got one of those injuries where you're not sure how long it's going to take," Marsh told Liverpool's official website.
"He's still getting treatment - with a bit of luck that will improve in the next couple of days and he'll be available for Saturday."
Liverpool currently sit sixth in the table.