The 37-year old joins the Glasgow club on a free transfer.
Could Manchester United assistant manager Ryan Giggs become the new Nottingham Forest boss?
The final matches from Group A are contested this evening, with France already through to the knock-out stages.
The Norwegian was able to sign off by guiding the Hoops to their fifth Scottish Premiership title in a row.
Arsenal have reportedly joined the race for Lille star Sofiane Boufal.
Glasgow Rangers and Derby County are also reportedly interested in signing Blackburn Rovers’ Grant Hanley in the summer transfer window.
Northern Ireland captain Steven Davis has committed his future to the Saints by signing a new three year contract
Jose Mourinho is hoping to complete a deal to sign the midfielder from their Premier League rivals.
West Ham United have already lodged one bid for Bournemouth striker Callum Wilson this summer.
Rangers are reportedly in talks to bring James Vaughan to Ibrox.