The 23-year-old scored his maiden goal in the elite European competition to boost the Dragons’ chances of qualification
The Nigeria left-back broke the deadlock in the 39th minute after pouncing on a rebound which came from a corner-kick.
Sanusi was in action for 90 minutes and he produced a man-of-the-match display as Porto sent Marseille packing from the Champions League.
The 23-year-old’s strike at the Orange Velodrome was his goal for the Dragons since he completed a permanent switch from their league rivals Santa Clara in the summer.
Later in the second half, both teams had a player sent off and Sergio Oliveira doubled the visitors’ lead from the penalty spot.
Mali striker Moussa Marega saw 79 minutes of action for Porto while Senegal‘s Mamadou Loum was introduced for Oliveira on the stroke of full-time.
The Portuguese giants are second in Group C with nine points after four games, behind leaders Manchester City while Marseille languish at the bottom of the table with no point.
Next up for Porto in the Champions League, is a home against Manchester City on December 1 but they visit Sanusi’s former club Santa Clara for their Primeira Liga fixture on Saturday.