The Black Cats bagged an early advantage thanks to Darren Bent's strike after 15 minutes.

But Nigerian midfielder John Utaka turned things around with a header three minutes before the break and a stunning finish from Younes Kaboul's through-ball after 58 minutes.

The action took place on the back of vociferous protests against Pompey's owners from hundreds of home supporters outside the directors' entrance prior to kick-off.

Deafening chants of "we want our club back" and "sack the board" rang throughout the ground as the club struggles to pay its players, continues to fight a transfer embargo and faces a winding-up petition from HM Revenue and Customs next month.

Boss Avram Grant clearly shares the fans' frustrations. After cancelling Friday's pre-match press conference, he also sat out the post-match interviews to avoid another string of questions about Pompey's off-the-field issues.

His place was taken by Groves and the coach paid tribute to his side's ability to put their team's financial woes to one side.

He said: "It was fantastic spirit from the players. What they showed on that pitch was great togetherness and they came away with a great result and good reward for it.

"I also have to give credit to the fans for the way they got behind us.

"They showed their frustrations, no doubt, but once they came into the stadium, they got behind the players.

"I think the players focused on the game in hand. It's a difficult task to play Sunderland, but they were well-focused on making sure they got a good result and a good performance."

Another off-the-field issue Pompey have had to contend with this week is heavy speculation linking goalkeeper David James with a move to Stoke.

Despite reports from BBC Radio Stoke on Friday claiming the deal was complete subject to a medical, James was in attendance at Fratton Park.

Asmir Begovic covered for him between the sticks, meaning James would be available to represent the Potters in the FA Cup, should they beat Arsenal on Sunday.

But Groves said: "David is around and has been around. As far as I'm aware, David is still here."

Sunderland boss Steve Bruce felt his side were unlucky not to leave Fratton Park with a replay after David Healy was controversially denied a late equaliser.

Paulo Da Silva headed Bolo Zenden's corner across the face of goal with two minutes left and Healy was certain he had touched it over the line in the scramble that ensued.

Bruce said: "Some would say the ball was over the line and David was convinced it was over the line.

"Obviously, I couldn't tell from where I was but we needed that little bit of luck to maybe turn the corner.

"There was a header towards goal and I think David hooked it over the line.

"But I've only seen it from one angle and whether it was over the line, I don't know."

Despite this decision proving costly for the Black Cats, Bruce was far from happy with his side's defending.

He was particularly fuming with goalkeeper Craig Gordon, who was caught in no man's land for the first goal, allowing Utaka to head over him.

Bruce added: "They were basic, bad goals to give away.

"The first one was a punt from the halfway line. Utaka got a header and the goalkeeper slipped out of position.

"At this level, you have to give yourselves a chance and we must defend better than we are at the moment."