Ex-Pompey triallist Paul Paton has signed for League One rivals Plymouth Argyle.
The Northern Ireland midfielder spent the first part of last week training with the Blues at their Roko training base.
However, the club opted not to offer the 30-year-old a contract.
Nevertheless, Paton - who was released by Scottish Premier League outfit St Johnstone in January - has subsequently won a deal at Plymouth.
The Scot will go into Derek Adams' squad to face Bristol Rovers on Saturday.
The former Dundee United man will also come up against Pompey next month when they travel to Home Park on April 14.