The highly-rated Mattock had been strongly linked with a move to the club but he is not the target that Coppell is closing in on.
Instead reports claim it could be Dagenham’s left-back Scott Griffiths, who is likely to be in action against the Royals in the Carling Cup tonight and has been watched by scouts.
Coppell told the Evening Post: “We are still searching and I think we are getting nearer – something could be done before the weekend.
“If we do something it will probably be the only signing we make, but I can’t say for sure.”
Steve Cotterill has been sacked by Birmingham the club have announced - with Garry Monk in pole position to replace him as manager.
Bundesliga top-four rivals RB Leipzig and Borussia Dortmund had to settle for a share of the points with a 1-1 draw at the Red Bull Arena.
Steve Cotterill has left Birmingham with Garry Monk in pole position to replace him as manager, Press Association Sport understands.
Walsall manager Jon Whitney stressed that his whole Saddlers side deserved to be praised following their 3-0 win at Southend United.
Paris St Germain forward Neymar has undergone 'successful' foot surgery.
Chris Coleman was pleased with the character shown by his Sunderland side - but frustrated to have to settle for a point in their 1-1 draw at Millwall.