Keegan was sent off during Saturday's abandoned Championship fixture at Charlton. Heavy rain in south London saw the game called off at half-time with Rovers leading 3-1. While the result does not stand, under Football Associaton rules the red card does so the midfielder will miss the second round tie as he serves a one-match ban.
Dean Furman is likely to replace Keegan in what will probably be the only change that manager Paul Dickov makes to his starting line-up.
Harry Forrester has resumed training and featured in a development squad game last week but it is too early for him to be considered. Fellow midfielder Marc De Val Fernandez continues to recover from a torn medial ligament.