Sent into the fray in the 76th minute in place of Josef Martinez, Dominic Iankov scored the winning goal in the 89th minute, with a low shot that surprised goalkeeper Andrew Rick.
Ruan added a valuable insurance net during stoppage time.
Martinez, in the first half, and Bryce Duke in the second half scored the other goals for CF Montreal.
On the Union side, Quinn Sullivan and Jesus Bueno deceived the vigilance of Jonathan Sirois in the first half.
CF Montreal (5-8-7) thus ended a four-game winless streak.
A week of two matches awaits the Montreal team. On Wednesday evening, they will be in New York to face New York City FC. Next Saturday, Laurent Courtois’s team will host the Vancouver Whitecaps.
Two halves in one
Perhaps a little affected by the rather chilly weather above the Saputo stadium, the players from both teams took a good twenty minutes before creating interesting chances to score.
Once the first occurred, the brave spectators in the stands saw the game come alive, but to the advantage of the visitors.
The Union opened the scoring at their first opportunity, in the 29th minute.
Posted in the centre of the penalty area, Sullivan received a back pass from Nathan Harriel and his shot, low on the pitch, deflected off the vertical rod to the right of Sirois before rolling into the net.
Some seven minutes later, CF Montreal brought both clubs back to square one when Martinez, with the help of an explosive drive, headed a Duke corner past Rick.
However, the Union was able to regain a one-goal lead in the 41st minute when Bueno was able to sneak to the edge of the net and push the ball with his right foot behind a Sirois who could do nothing about it.
The Montreal clan did not let this goal demoralize them. He started the second half with confidence and stayed deep in opposition territory.
This constant presence in the rival zone led to the equalizing net in the 56th minute.
From outside the box, Duke lobbed a free kick that eluded the Union goalkeeper and ended up in the net.
Duke was credited with the goal, although it appeared Union defender Jack Elliott touched the ball before it crossed the goal line.
The Montreal team continued to control the tempo in the second half and the perseverance of Laurent Courtois’ men would ultimately pay dividends.
