Mariner is relishing the prospect of pairing O'Dea with ex-Manchester United defender Richard Eckersley in the centre of his defence.
"I think Darren and [Eckersley] will be a formidable pair," Mariner said. "You've got the aerial ability from Darren and the pace in behind with Eck.
"He's a different specimen," added Mariner on O'Dea. "What it is - I've been saying this to the young players for quite some time - it's all about habits. Darren has fantastic habits on the field, off the field. You can see just the way he commands himself, I think the fans are really going to take to this kid."