Sahar: Grabbed two first-half goals
Sahar opened the scoring after seven minutes from Arnold Mvuemba's through ball then headed in a Glen Johnson cross 10 minutes before half-time.
It took until five minutes from time before Pompey again breached the defences of last season's FA Cup heroes, Mvuemba getting on the scoresheet himself with a long-range effort.
Johnson, who also hit the bar, rounded off the scoring in injury time with an angled strike.