On-loan QPR striker Campbell sustained ankle damage during training at the end of last week and wore a protective boot to attend Wednesday night's FA Cup quarter-final replay defeat to Millwall.
Widemen King and Olsson left the action early due to hamstring problems but have a chance of recovering in time to face the Clarets.
Young forward Anton Forrester came on for a first-team debut in place of King only to suffer a similar complaint while playing for Blackburn's Under-21 side on Thursday.
Bradley Orr (ribs) is sidelined alongside fellow right-back Adam Henley (hamstring), who is expected to join Dickson Etuhu (knee) in being out for the season.
Forward Colin Kazim-Richards and midfielder Lee Williamson remain out due to ankle problems.
David Bentley suffered medial knee-ligament damage in the initial game at Millwall last weekend but Rovers' remaining loanees, midfielder David Jones and winger Cameron Stewart, are in contention once more having been cup-tied.
Josh Morris was also unavailable against the Lions having played in an earlier round while on loan for Rotherham and is set to return.
There was some positive news for boss Michael Appleton in midweek, as full-back Martin Olsson returned from an eye problem and club stalwart David Dunn completed 90 minutes for the first time in a season dogged by persistent calf trouble.