Martin O'Neill will not discuss deals with his out-of-contract players until Sunderland's Premier League fate this season is decided.
Defenders Titus Bramble and Matt Kilgallon are in the final months of their current agreements, and Bramble has consistently said he would like to stay.
The centre-half is back in favour and has started 10 games in succession, but with Sunderland in a fight for Premier League survival his future will remain unclear until the summer.
O'Neill told the Sunderland Echo: "Now, at this minute, the most important issue is trying to get points on the board.
"I know it's a cliche, but those things can wait."
Sunderland have taken just two points from a possible 18 and go into this weekend's game against Norwich just six points above the bottom three.
O'Neill's side face a daunting run of fixtures after Norwich as they take on Manchester United, Chelsea and Everton either side of a derby at Newcastle.
The match is being organised in conjunction with the club's proposed new owners the Pompey Supporters' Trust, with all proceeds going towards their community stake in Portsmouth, and will take place at Fratton Park on Tuesday, April 16.
Defender Hreidarsson, 38, who made 123 appearances for Pompey, is paying the expenses to bring his side to the south coast as part of an eight-day tour of England ahead of the new Icelandic Premier League season.
PST chairman Ashley Brown said: "We were delighted when Hermann approached us with this idea. This is a fantastic opportunity for fans to come and say farewell to a terrific club servant, but more importantly contribute to the biggest community share yet.
"Every penny will be reinvested in the club as part of the PST's shareholding, so this means any fan can have their stake in Pompey simply by buying a ticket for the match.
"More details of prices will be announced soon, but no standard ticket will cost more than ?10, so we feel this is a great way to make community ownership accessible to all."
Hreidarsson, who has recently been in England to complete a coaching course, added: "It is a great opportunity for my players to play at a legendary ground and all the money will be going to a great cause.
"My time at Pompey was a rollercoaster ride, with some terrific highs like winning the FA Cup in my first season and also some difficult times, which saw some good people lose their jobs.
"All the time, though, the Pompey fans were different class and I didn't feel I got the chance to say goodbye to them properly after I was left for Coventry in 2012."
The 24-year-old South Africa international is hoping to be included in Doncaster's squad for Saturday's home game with Portsmouth.
Furman is currently in his fourth season at Boundary Park after signing from Rangers in 2009 and has made over 120 appearances for the club.
He began his career at Chelsea under Jose Mourinho then moved to Ibrox in 2008 and had a loan spell at Bradford before signing a three-year deal with the Latics in the summer of 2009.
Furman made his debut for his country in a friendly against Brazil in September 2012 and earned the man-of-the-match award in South Africa's 2-0 win over Mozambique later the same year.
The club revealed he had agreed to continue his involvement with the Dons as a non-executive director.
In a statement on the Aberdeen website, Brown said: "Having reflected long and hard on the situation, I felt the time was right for me to step down as manager."
The 72-year-old took over at Pittodrie in December 2010 after leaving Motherwell but he has struggled to achieve lasting success at the club.
Brown, whose assistant Archie Knox will leave the club in the summer, added regarding his decision to retire: "I feel it is important this is out in the public domain as I do not want anything to distract from the playing side over the next few weeks.
"Archie and I are determined to do whatever we can to help the team finish 2012-13 on a high and we strongly believe we will be leaving a solid base for the next management team to build on."
Although he led Aberdeen to two semi-finals - they were also in the League Cup semi-finals when he arrived - he could not secure a top-six place in the Scottish Premier League last season after taking them away from relegation trouble in his first campaign.
And the announcement comes after a goalless draw with Motherwell on Saturday left Aberdeen in ninth place with three games left to the split.
The Dons are two points behind sixth-placed Hibernian but face Celtic at Parkhead on Saturday and look destined to finish in the bottom six for a fourth consecutive season since Jimmy Calderwood lost his job on the day he led the club into Europe.
