Leicester turned down Leeds' request to speak to O'Neill last week, but Ridsdale said: "I will be putting in another call to Leicester today in the hope that they will allow Martin to speak to us."
Middlesbrough are facing a growing injury crisis on top of Paul Gascoigne's absence. Gary Pallister will be out for five weeks after knee surgery.
Blackburn have turned down a transfer request from Billy McKinlay, the Scottish international midfielder.
John Rudge's position as manager of Port Vale continues to hang in the balance. Rudge, whose 19 years at Vale include nearly 15 as manager, called for "clarification" from the chairman, Bill Bell, after Stephen Plant reportedly resigned from the board in protest against a proposed cut in coaching staff.
But a statement insisted that Plant was voted off because of "serious misconduct". The board are "concerned and upset by the team's performances".
Arsenal have sold out Wembley for their next Champions' League match, against Dynamo Kiev on 21 October.Reuse content