Millwall moved five points clear of the Championship relegation zone with a narrow 1-0 victory over Portsmouth at The Den this afternoon.
N'Guessan, handed his first start in 15 games, scored the only goal of the game to move the Lions just a point behind their opponents in the table.
The former Leicester man guided the ball past Stephen Henderson in the Pompey goal after Liam Trotter had knocked Liam Feeney's cross on into his path.
Republic of Ireland international Liam Lawrence had the visitors' best chance to open the scoring but he sent a close-range header wide.
However it was the home side who were the better side and threatened through substitute John Marquis, who sent a shot narrowly past the post.
Brian Howard also went close with a free kick before N'Guessan finally broke the deadlock with his 82nd-minute winner.
