Mohammad Reza Azadi opened the scoring for the host in the 14th minute and in the 32nd minute Mumbai City defender Halen Nongtdu looked to pass the ball back to his goalkeeper Phurba Lachenpa but could not locate him accurately and instead sent it into the back of his own net.
Amimahdi Janmaleki received a direct red card for a high-footed reckless challenge on Sanjeev Stalin midway in the 68th minute.
The result means Mumbai City will continue its pursuit of a first point and a first goal in the campaign when it hosts Navbahor on the final matchday while Nassaji bow out from Riyadh where it takes on Al Hilal SFC next.