Michael Ledger has completed his loan switch to Viking Stavanger.
Ledger spent time on trial in Norway and has now completed his expected move. The 20-year-old moves until the end of the season.
He made 11 appearances for the U23's last season, who recently strengthened their defensive options with the signing of New Zealand youngster Sam Brotherton.
Brotherton started the 3-1 defeat to Manchester United on Monday night, part of a side that also included Jan Kirchhoff, George Honeyman, Donald Love and Lynden Gooch.
Ethan Robson played alongside Kirchhoff in midfield and has called on his team to make big improvements for the visit of Leicester City to the Stadium of Light this Sunday.
Robson told safc.com: "We had plenty of opportunities and if we had taken them then it would’ve been a different story,
"It was frustrating but we find ourselves in this position again and we have got to look to Sunday’s game now.
“Leicester is a big game for us now and its one we need to perform in so we get back to winning ways.
“We always try to look to the positives – at Blackburn last week it was a good game for us and we showed great character to get back to winning ways from the Burnley game,
"We now find ourselves needing to respond again and this weekend we must deliver a performance that’s worthy of three points"