Several attempts by Kotoko midfielder Baba Mahama finally yielded dividends in the 34th minute when he was brought down in the box by the skipper of Wassaman, Daniel Paha Kwofie.
Referee Prince Amoah, who was close by, awarded a spot kick which Amos Frimpong converted beautifully to give Kotoko the only goal of the match.
Moments after the goal, Kotoko mounted incessant pressure on the visiting team, forcing a defender of Wassaman to use his hand to hit the ball in their penalty box, but the referee ignored a penalty appeal by the Kotoko players.
Substitute Cobby Anyormi of Wassaman had a bright opportunity to bring his side at par when he was put through in the box, but he shot widemuch to the relief of Kotoko players and the sparse home supporters.
Stephen Sarfo, Alfred Nii Okai Quaye, Michael Yeboah and Stephen Sarfo were on target to seal a famous win for Chelsea.