Sporting KC goalkeeper Jimmy Nielsen punched away Ferrari's header in added time as Montreal struggled to a 0-0 draw Saturday.
The Impact picked up their first point in three games since ending a five-game winning streak which had put the expansion team into playoff contention.
"It was unlucky because I took the ball very clear," Ferrari said. "It was a great pass from Marco. Just unlucky."
The Impact claimed their 40th point with the draw, which kept them unbeaten in their last seven at home. Montreal, which is seventh in the Eastern Conference, had won its six previous home games since a 3-1 loss to Sporting KC on July 4.
"Honestly, I was feeling before this game that everything was almost done, and also we know that we were playing against one of the best teams in MLS, and you see on the field how they are," Ferrari said. "But I think we played a good game today and we tried everything to win the game. It was not easy, 0-0. We don't have a lot of draws this season."
The Impact have three games left in their season with two on the road. The draw left them six points out of the final playoff spot behind fifth-place Houston, which has five games remaining, including hosting Montreal's next game on Oct 6. Sixth-place Columbus enters its Saturday night game in Chicago with 45 points.
"At the end of the day, until somebody tells me that we're mathematically out of it, we're still in it," Impact captain Davy Arnaud said. "The only thing we can now go do is win our next three games and hope that it's enough. We know it's going to be difficult because teams already have close to the points that we can possibly get, but until we're out of it we're going to keep on pushing."
Montreal's path to the playoffs is as unclear to Marsch as its prospects are bleak.
"I wasn't a math major in college so I'm not sure but it certainly starts to feel like the points are working against us," Marsch said. "We obviously have an eye on results around the league. We know that we're on the outside looking in, and with games in hand and everything it's not a great situation for us, but we're not stopping. As long as there's still a little light at the end of the tunnel, whatever, this team's given it everything they've had, every day, all year long, and for sure we're not stopping now."
Kansas City is undefeated since July 28, with a 5-0-3 streak since a 2-1 home loss to Columbus.
Sporting KC, which leads the East with 56 points, is 8-4-3 on the road this season.
"This was a massive point for us, for sure," Kansas City coach Peter Vermes said. "A huge opportunity for us to not necessarily separate ourselves immensely, but every one of those points adds up at the end of the season."
Marsch signalled Montreal's need for the win and its crucial three points when he substituted midfielder Sanna Nyassi for defender Alessandro Nesta 57 minutes in a bid to spur the offence on a rainy afternoon at Saputo Stadium.
The Impact came close when Arnaud shot just wide of the left post from the right side of the box in the 69th minute.
Nyassi made a strong run through the right side of the penalty area in the 80th minute but was ridden off by Kansas City defender Seth Sinovic. No foul was called though Sinovic used his right arm to lock up Nyassi.
Montreal goalkeeper Troy Perkins made a point-blank stop on Kei Kamara 14 minutes in on his way to the clean sheet.
The Impact are 10-3-3 at home this season, including a 2-1-2 mark at Olympic Stadium while renovations were completed at Saputo Stadium to increase its capacity.
Justin Mapp had the Impact's best opportunity in the first half. His shot went wide of the left post.
Sporting KC midfielder Jacob Peterson was on the bench after coming out of the game when he was shown a red card by referee Jorge Gonzalez in the 90th minute.
"I think the referee misunderstood what he said, I really believe that," Vermes said. "I think he thinks that he actually made a comment to him about his performance and it wasn't even remotely close. We'll need to see the referee's report when it comes out but I think he definitely heard something that he really didn't say."
Arnaud and Impact midfielder Collen Warner both were shown yellow cards. Warner will miss Montreal's next game in Houston on Oct. 6.Suggest a correction