Gary Roberts won and scored a late penalty as Portsmouth won 2-1 at Plymouth.The winger was felled by left back Gary Sawyer as he drove in from the right to convert Pompey's second penalty of the game. Matt Tubbs had fired the visitors into a first-half lead while Gregg Wylde grabbed a last-minute consolation for the hosts.Plymouth keeper Luke McCormick made a superb second minute diving save to deny Gareth Evans as the Portsmouth danger man strode through the middle of the home defence.In the 17th minute McCormick was again sent full stretch, palming over Kyle Bennett's rising drive from the edge of the box.Portsmouth took the lead in first-half stoppage time when Tubbs drilled the ball down the middle from the spot after Portsmouth's Enda Stevens was adjudged to have been felled by Harim Boateng.A few minutes earlier 19-year-old Boateng has smashed a downward volley over the bar.Graham Carey came close to scoring for Plymouth with a superb dipping volley which keeper Brian Murphy did well to palm out and over from under his bar.And Roberts secured the win in the 86th minute when he was brought down by Sawyer and netted from the spot before Wylde pulled a goal back three minutes later.