The Malian outfit were aiming to make the most of home advantage at the Stade Modibo Keita in the first-leg encounter.
Yet it was the Tunisian side who drew first blood in the tie, Haythem Jouini making the breakthrough in the 27th minute.
The visitors held onto their lead until the break, and it looked as though ES Tunis would maintain their one-goal advantage ahead of Friday's return leg.
However, Moussa Doumbia restored parity 12 minutes from time to leave the tie nicely poised.
In Saturday's other second qualifying round match, Nkana's hopes of progressing were hindered by a 0-0 draw at home to Egyptian outfit Zamalek.
The Zambian hosts applied plenty of early pressure at Nkana Stadium, but failed to build on their promising opening and face a difficult task against Mido's men in the return leg.
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