Wales defender Neil Taylor accidentally kicked the Serbian, 27, while they both tussled for the bouncing ball.
Tadic, who has been in fine form for both Serbia and Southampton this season, may need surgery.
The draw in Cardiff left Serbia second in the group, two points adrift of leaders the Republic of Ireland.
Southampton forward Dusan Tadic may have broken his nose during Serbia's 1-1 draw against Wales in their Group D World Cup qualifier in Cardiff.