The 28-year-old Senegal international had been poised for a season long loan deal with the South London club until a last minute bid from Pompey came in.
Cisse has moved to Fratton Park on a two-year contract with Blues receiving a £300,000 transfer fee.
Ironically, Cisse's first Premiership game for his new club could well be against Blues as we travel to Fratton Park on the opening day of the season on August 14th.
We wish him well during his time at Fratton Park.
Meanwhile, reports suggest that with the departure of Cisse to Portsmouth, Blues boss Steve Bruce could now offer a deal to former Pompey favourite Darren Anderton. The 32-year-old one-time England international midfielder is a free agent having been released by Spurs at the end of last season.
