Ali Maaloul put Ahly ahead in the first half with a penalty (Photo: the club s official Twitter account)
Tunisian full-back Ali Maaloul dispatched a 19th-minute penalty to put Ahly in front but USGN secured a famous draw with a second-half goal at the General Seyni Kountche stadium in Niamey.
Ahly, who are eyeing a third successive Champions League title, failed to impress in a scrappy affair but they will be overwhelming favourites to advance to the group stage when they host USGN in the second leg next weekend.
USGN's keeper needlessly rushed out and clattered into Ahly striker Mohamed Sherif after he controlled a long ball in the area, with spot-kick specialist Maaloul sending him the wrong way to open the scoring.
Ahly then relied on repeated long balls that were no trouble to USGN's defence.
However, only one hopeful ball upfield evaded the defence and found winger Taher Mohamed Taher early in the second half, but he mis-controlled it and was thwarted by the advancing keeper.
Ahly's sluggishness was punished when a poor headed clearance from Hamdi Fathi was pounced on by a USGN forward, who outjumped right-back Mohamed Hani to flick into the path of unmarked striker Moumouni Djibril Diori to volley home from close range.
The visitors piled on pressure in search of a late winner and substitute Akram Tawfik had a strong penalty claim waved away by the referee as USGN escaped with a valuable draw that keeps alive their hopes of causing a huge upset.
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