Morgan came on as a substitute in the 2-0 defeat at West Brom on Boxing Day and collected his fifth booking of the season so will serve a one-game ban.
Fellow defender Gabriel Zakuani remains Mark Cooper's only injury concern ahead of the game.
Zakuani has been playing through a persistent groin problem in recent weeks and only managed 75 minutes at The Hawthorns. Should the former Fulham man not be passed fit to face the Bluebirds then Charlie Lee or Tommy Rowe could come in at full-back.
Posh returned to the bottom of the Championship on Boxing Day after Plymouth Argyle surprisingly beat Cardiff, so Cooper's side need a win to keep in touch.