Though the Black Cats boss would not comment on the club’s pursuit of Exeter City full-back Josh Key, he said that he hoped that the club could make a breakthrough in the next week or so.
Johnson remains eager to strengthen his currently threadbare options at full-back, with Carl Winchester and Dan Neil stepping into those roles at Harrogate Town.
Both impressed their head coach in an emphatic 4-0 win, but Johnson knows the need to strengthen.
He also at a minimum wants to add another centre-back and another striker following the departure of Charlie Wyke.
Responding to questions on the club’s interest in Key and Nottingham Forest right-back Jordan Gabriel, Johnson said: “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.
"They're 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.”
Johnson hailed his Sunderland players for their flexibility as the produced an accomplished display at the Envirovent Stadium, and said that he was confident he would field a side capable of beating Wigan Athletic on the opening day of the league campaign.
Luke O’Nien made his first appearance of pre-season against Harrogate Town to further bolster his options through the midfield and forward areas.
“Whatever we go into the start of the season with, we are going to die in a ditch to get the result,” he said.
“Sometimes you can say things in the media and it can get a little bit sensationalised as is natural, but the main point is we're grateful for what we've got at the moment and we massively believe in the players that we have.
"Whether they're our young players, Dan Neil stepping in at left back and showing he's bright enough and intelligent enough to do that despite never having played there.“OK, it might be different playing there against one of the best wingers in the league. We know what we need to get, we're trying hard and I believe we'll get there, but whatever we go into the season with they will be ready.
"Then we can add in to supplement as we go.”
Johnson also allayed any injury concerns surrounding influential winger Aiden McGeady, who was not part of the squad.
Jack Diamond excelled in McGeady’s absence and Johnson confirmed that he expects to have the Irishman back available soon.
“McGeady had his injection, with his tendonitis in the knee, so that pushes him out for eight or nine days,” he explained.
"That was always in the plan. We tried to build his base fitness up, so it should be easier to then push him back again going into the season.”