Josh Martin has signed a contract extension that keeps him at Fratton Park for the remainder of the season.
The 22-year-old winger initially penned a short-term Pompey deal back in November, having impressed in a spell training with the club.
He was immediately handed a debut in a League One clash with Blackpool and has featured on four occasions, including in wins at Burton and Northampton.
Blues boss John Mousinho said: “Josh is a talented player and we know he has all the attributes required to fit into this team.
"Josh is a talented player and we know he has all the attributes required to fit into this team."
“We still think that there’s a lot to come and I’m delighted to get the chance to work with him for the rest of the season.”
Former Arsenal trainee Martin turned professional with Norwich and made 16 appearances for their first team.
Five of those came in the Premier League at the conclusion of the 2019/20 campaign, with outings against the likes of Chelsea and Manchester City.
He has also spent time on loan at MK Dons, Doncaster and Barnsley, netting three times in 23 games for the latter club last term.