Davis was suspended for last week's victory over Portsmouth and was all set to return against the Potters before picking up a knee injury during training.
The former Tottenham midfielder is now rated as doubtful for the clash at the Reebok Stadium and could be joined by O'Brien on the sidelines as he continues to struggle with a minor groin injury.
However, the good news for Megson comes with the return of Elmander who missed last Saturday's game with a calf strain, but is now expected to lead the line against Stoke while Ricardo Gardner could also feature having missed the last six weeks.
"Sean has got a problem with his knee and Andy has been overdoing it a little bit in training with his core work. We're hopeful that they will both be okay," said Megson.
"But the ones who were not available last weekend should now be all right to play ? Johan Elmander is fit, and Bibi Gardner has trained all week - so they should be fine."