Newell's, looking for their sixth league title, lead by one point from Banfield, who lost their unbeaten record in a 2-1 upset at home against lowly Racing Club on Sunday.
With three games to go, Newell's have 36 points, Banfield 35, Colon 31 having played one more match, and title holders Velez Sarsfield 30. Estudiantes also have 30 but are out of the running with only one match left before heading for the Club World Cup in Abu Dhabi.
The 1.95-metre tall Boghossian showed control normally associated with smaller strikers like Lionel Messi, turned three defenders one way, then the other and placed a low shot inside the bottom corner in the 65th minute.
Newell's spent the last 20 minutes defending their lead with 10 men after midfielder Hugo Barrientos was sent off for time wasting, having been booked earlier.
Colon midfielder German Rivarola, who had a chance to equalise but was foiled by Newell's goalkeeper Sebastian Peratta, was also sent off at the end of the six minutes of stoppage time.
As the final whistle sounded amid the loud celebrations of Newell's large contingent of fans at the ground known as the Elephants' Graveyard, Rivarola kicked the ball into the backside of referee Javier Collado.
It was not clear from video replays whether the kick was intentional but Collado interpreted it as such, showing Rivarola the red card and unleashing seething protests from the midfielder's Colon team mates.
Collado needed protection in the middle of the pitch from riot police carrying shields until the players calmed down.
