Steve Claridge scored twice to help Alan Ball's Portsmouth gain revenge on Crystal Palace less than a month after their 4-0 hammering at Selhurst Park.
Palace opened the scoring through central defender Andy Linighan whose powerful header gave goalkeeper Andy Petterson no chance.
But it was a goal against the run of play as Portsmouth pushed forward in the opening exchanges only to see their best efforts denied by the brilliance of goalkeeper Fraser Digby.
Former Palace striker Lee Bradbury, who played a key role in Portsmouth's downfall in the game at Selhurst four weeks ago, turned the tables on his old club and was a constant threat.
But it was his strike partner Claridge who brought Portsmouth back on level terms after 43 minutes when Digby was unable to hold a goalbound shot and the former Wolves and Leicester striker bundled it over the line at the second attempt.
In the second half, Palace looked weary and Bradbury took advantage of his old club when a mix-up between Dean Austin and Linighan sent him clear.
The former soldier sprinted 30 yards with the ball at his feet and although Digby did well to get a hand on his shot, it was not enough to stop the ball going in the net.
Claridge completed Palace's misery with his second goal of the afternoon as Steve Coppell's men were unable to clear a free-kick and the Portsmouth front man turned the ball home from a narrow angle past the stranded Digby.
Had it not been for the brilliance of Digby, Palace could have suffered an even heavier defeat with Portsmouth's Sammy Igoe twice denied from two yards out thanks to the reflexes of the former Swindon goal keeper.
Bradbury also hit the post in the first half and Portsmouth goalkeeper Petterson had just one other save to make from another Linighan header at a set-piece.