With the Iraqi league suspended due to the civil unrest in the country, the 2012 runners-up headed into Tuesday's quarter-final first leg having not played a competitive game for over two months.
But, despite their lack of fixtures in recent times, the visitors showed their quality in Vietnam with a slender victory.
Both teams had scored 19 times in the competition prior to the encounter, however, just one was needed on this occasion for the Ayob Odisho's men.
And it was Radhi that found the net for only the second time in the tournament, firing home in the 45th minute.
Ha Noi were unable to find a leveller in the second half, meaning that they will have work to do to turn the tie around in the second leg, which takes place next Tuesday.
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