Although Regis Le Bris will have to go without the influential defender on Thursday, the scan results provided a major boost for the Black Cats after Ballard was forced to miss the home draw with Leeds.
“He is getting better, but he won’t be available for the game tomorrow," said Le Bris in his pre-match press conference.
"We hope [he will be available] for the next fixture, but we will have to wait and see. It’s not serious."
RECOMMENDED READING:
With Ballard set to miss the City game, Le Bris must decide whether to stick with the same back four of Trai Hume, Nordi Mukiele, Omar Alderete and Dennis Cirkin against Leeds or to mix it up.
Sunderland's head coach could drop Lutsharel Geertruida into the defence if he wanted to switch to a back five, and also has Luke O'Nien available, though the club captain hasn't started a single game so far this season.
Le Bris must also decide whether Cirkin is able to play a second successive game after making his first start of the season against Leeds following his lengthy spell on the sidelines out injured.
Cirkin was a key player for the Black Cats last season but missed the first half of the Premier League campaign after undergoing surgery on a longstanding wrist problem in the summer.
Cirkin's long-term future remains uncertain with his current contract due to expire at the end of the season as things stand, but Le Bris was thrilled to see the left-back back in action.
He said: "Really happy. He had a tough period and the way he helped the team last season was impressive, he was really good.
"Sometimes you can have tough periods and it's tough to regain your confidence and you can get into a bad cycle. We supported him really well, the club, the staff and teammates."
Sunderland will climb to fifth in the Premier League table with a win on Thursday (8pm kick-off) but have very recent experience of City's quality having suffered their heaviest defeat of the season against Pep Guardiola's side early in December.
Reflecting on the 3-0 defeat at the Etihad, Le Bris said: “We had a deep analysis, and we reviewed the game with the squad.
"We had some good things, but obviously they are strong in different areas. We struggled after 30 minutes, they found a solution to score from a shot and then from a corner kick. After that, the game was different because, 2-0 down, I think is totally different.
"I hope we will use the negative to get better, and the positive as well because we were able to play and create chances.
“After the two goals, the game was different because they are smart and able to manage different scenarios. When they scored those two goals, they were able to defend a bit differently. Maybe we had a few more opportunities to get into the attacking half.
"But at the same time, they were able to manage more counter-attacks, and they are excellent in this part of the game. They created more chances when we were a bit more open."
Since that defeat at the Etihad, Sunderland are unbeaten in three games and have conceded only one goal. They're yet to taste defeat at the Stadium of Light this season.
Le Bris said: “It’s a question of belief, and energy as well because I think we have a really good energy at home, with our fans.
"This connection with the stands and the crowd influences the game, it’s really clear. It’s one more strength for us and we have to use it when it is possible."