Sulley Muntari slots past Rio Ferdinand from the penalty spot to send Pompey to Wembley.
The midfielder kept his cool as the Blues pulled off a famous 1-0 FA Cup quarter-final victory at Manchester United in March 2008.
Harry Redknapp’s men rode their luck but were rewarded for their dogged determination when Milan Baros was brought down by Tomasz Kuszczak.
The Polish keeper was given his marching orders as a result, forcing Ferdinand to don the gloves.
But the defender could do nothing to keep out Muntari’s spot-kick as Pompey triumphed at Old Trafford, before going on to lift the Cup with wins over West Brom and Cardiff.