The duo picked up knocks in the win at Plymouth on Saturday and a decision to include them will be made just before kick-off.
Watson played in the 2-1 victory at Home Park while Johnson has been excellent while he has been at Hillsborough - and have even stated on more than one occasion that he would like to stay at Hillsborough.
Should Watson recover in time, Brian Laws has a tough choice to make in midfield with Glenn Whelan coming back from a one-game suspension.
Yoann Folly came in from the cold at Plymouth and played really well so the Frenchman will be disappointed if he is not included tonight.
Former Owls player Chris Brunt is expected to be part of the squad in a game where he will face his old club for the first time.