Charlton moved eight points clear at the top of League One as Dany N'Guessan scored the winner to defeat Walsall.
N'Guessan grabbed his third goal in five games since joining the Addicks on loan from Millwall when he headed in from Johnnie Jackson's free-kick.
Walsall, who lost for the first time in six games, had a good opportunity to equalise but Jon Macken shot off target after a mistake from Ben Hamer.
Bradley Wright-Phillips and N'Guessan also missed chances for a second goal.
Charlton will win promotion next Saturday if they win at Carlisle and Sheffield Wednesday fail to beat Colchester.