The reigning Ghana Premier League champions produced a competitive display against the five-time African champions and appeared on course for a goalless draw before a late goal decided the contest.
TP Mazembe created the first major opportunity in the 33rd minute when Chadrack Bingi-Belo found space inside the Medeama penalty area, but his header from a free-kick lacked direction and was comfortably gathered by goalkeeper Felix Kyei.
Medeama responded with a good opportunity of their own, with Dominic Amponsah denied from close range by TP Mazembe goalkeeper Marc Diouf.
Kyei was called into action again shortly before half-time, producing an important save to keep out Josue Kazema as the two sides went into the break level at 0-0.
Medeama continued to search for the opening goal after the restart and came close in the 64th minute when Emmanuel Annor tested Diouf from inside the penalty area, but the Mazembe goalkeeper made another crucial save.
With the match seemingly heading towards a goalless draw, TP Mazembe struck three minutes from the end of normal time.
Substitute Lise Ntumba Nyembo finished off a swift counter-attack in the 87th minute to give the visitors the lead and silence the home crowd.
Medeama pushed for an equaliser in the closing minutes but could not find a way through as Mazembe secured a valuable 1-0 victory.
The result leaves Medeama with a difficult task in the second leg. The Ghanaian champions will travel to Lubumbashi next week knowing they must overturn the one-goal deficit to advance to the second preliminary round of the CAF Champions League.
