Kenny Jackett is hoping to be back to full strength for next Thursday's second leg.
Portsmouth had been dealt a blow pre-match with first team regulars Lee Brown and Brett Pitman ruled out.
Jackett's side had looked short of firepower in Pitman's absence but the experienced goalscorer could return at Fratton Park.
“Lee Brown failed a fitness test this morning with an Achilles injury," Jackett said.
"Brett Pitman has an Achilles injury that he’s been nursing for a little bit. Hopefully, he’s on the road to recovery.
"Neither has been ruled out, and they should both have a chance for the second leg, although what type of chance, I don’t know.
"I’ll make a decision on it by Tuesday or Wednesday.”
Jackett insists his side are capable of coming out on top in the tie, but admitted they were lacking their usual 'explosiveness'.
Jon McLaughlin barely had a save to make despite the Black Cats playing with ten minute for the last quarter of the game, Alim Ozturk seeing red for a challenge on Gareth Evans.
“We’re a goal down and we understand that, but we have to look forward to Thursday and give it everything we’ve got," Jackett said.
"We’re capable of doing that. We have to put on a top-class home performance, and with a packed Fratton Park, that’s something I’m looking forward to as a manager.
“We’ll look forward to Thursday. It’s evenly poised. Obviously they’ve just got their noses in front, but we’re capable of coming back. It’ll be a passionate atmosphere at Fratton Park, and one we’re looking forward to. It’s a good opportunity for us.
“I thought we were the stronger side in the first half, but couldn’t get the strikes away," he added.
"Fair play to Sunderland, they defended well in the wide areas and our delivery into the box wasn’t necessarily there.
“Barring Gareth Evans’ two good strikes, we didn’t create enough, whether it was the first half or 11 against ten. We had a lot of the ball, but couldn’t get out delivery right and perhaps lacked a left-footer in terms of the balance of the side.
“We maybe didn’t have the explosiveness we usually have. It was difficult for us going forward, but we competed and battled well. It was a good quality strike from Maguire that’s got their noses in front, but it’s evenly balanced for Thursday night."
Jackett said he agreed with the decision to show Ozturk a red card. Sunderland are set to appeal in the coming days.
“I didn’t think the referee could do anything else," Jackett said.
"I thought it was a red card. Gareth is getting to the ball. He might have been a little bit wide, but he would have got to the ball and he would have been able to get a shot off."
Saturday night was the first time the Black Cats have come out on top against Pompey this season, and Jackett expects it to be another close encounter on Thursday.
“We’ve played four times now and there hasn’t been a lot in it," he said.
"We’ve won two, they’ve won and the other one was a draw. It’s always been very close, and it’ll probably come down to a few key moments on Thursday.
“That was the case here really. It was a good strike from Maguire, and we just couldn’t find that kind of strike for all of our efforts. Even so, it’s evenly balanced. We’ve got the home leg to come. We’re a goal behind, but we’re capable of getting that back."