Sunderland hoping to unlock deal for Exeter's Josh Key

The Black Cats tabled an improved bid of £1m for Key, with their offer also understood to include a series of potential add-ons, but while Exeter officials accept they are unlikely to be able to hold on to the 21-year-old, who can play as a full-back as well as a winger, they remain determined to hold out for the best possible deal.

Sunderland have also held talks over Jordan Gabriel, a right-back target who is set to leave Nottingham Forest after spending the bulk of last season on loan at Blackpool.

“We’re working really hard behind the scenes and a lot of that is to put yourself in a position where you've got the options,” said Johnson. “They're (Gabriel and Key) not our players and so I can't talk about them, as you know.

“You have a list, sometimes five, ten, and you've got to make sure it's a quality list and that it fits with what you're trying to do. They've got to be affordable, available and fit the club's philosophy.

“It's not easy but to be fair, I do feel like we are getting there in a couple of positions. My hope is that in the next week to ten days we're able to bring a couple in.”

Sunderland continued their pre-season preparations with an emphatic 4-0 win at Harrogate on Saturday

Elliot Embleton scored with two deflected first-half strikes, before Carl Winchester, who was playing at right-back, added a third goal after a move that involved Jack Diamond and Aiden O’Brien.

The Black Cats completed the scoring in the second half when Harrogate goalkeeper Mark Oxley palmed a deflected cross from substitute Ellis Taylor into his own net.

The game was played behind-closed-doors despite tickets having initially been sold to Sunderland fans.

Sunderland (4-3-3): Patterson (Burge 46); Winchester, Flanagan, Doyle (Younger 60), O;Nien; Embleton (Taylor 60), Evans (Wildin 60), Neil; Diamond (Hawkes 80), Stewart (Kimpioka 60), O’Brien (Grigg 60).