In the end, the Impact's 2-2 draw with the Los Angeles Galaxy, which saw a two-goal lead produced by Marco Di Vaio and Ignacio Piatti in the first half erased in the second on goals from Gyasi Zardes and Alan Gordon, was just more wasted points among many this season for the 5-16-6 club.
What counted for this night was holding a moment's silence before the game for Ouimette's sister Julie, who died Friday after a 12-year battle with cancer. She was 20.
The crowd of only 13,916 at Saputo Stadium stood at the 34th minute mark and cheered for Ouimette, who wears the No. 34 shirt.
Di Vaio, the Impact's leader and star striker, opened the scoring in the 28th and then ran immediately to the bench to hug the 22-year-old defender from Terrebonne, Que.
"We wanted to dedicate a victory to Karl and his family," said 38-year-old Di Vaio. "When I scored the goal, it was simple to go to him because he spent really bad moments the last few days.
"We wanted to give his family some positive emotion. We're a good group, a tight group. We're together in good and bad moments."
It had been a trying week for Ouimette, between the high of being invited to play for Canada's national team in Toronto and having to make a quick trip back to Montreal when his sister died.
He got one minute of playing time in Canada's 3-1 win over Jamaica on Tuesday night. He returned Wednesday morning and didn't expect to dress against the Galaxy, but coach Frank Klopas sent him on the field to replace injured fullback Hassoun Camara in the 59th minute.
It turned out to be an emotional night.
"It was great for Marco to come and see me, and everybody on the team gave me support before the game," said Ouimette. "I just came back, so it was the first time I saw them since my sister passed away.
"It was great to have the guys show they're there for me and have my back. It's a big gesture for my sister. The one that was most difficult was the minute of silence before the game. I was away, I'd been thinking about other things, trying to get past these emotions. It's hard not to have my sister next to me."
The Impact looked to have come up with a third straight win at home in a solid opening half, but injuries to defenders Matteo Ferrari (hamstring) and Camara (left elbow) opened the door for the high powered Galaxy attack in the second.
The Galaxy (14-6-7), who are chasing Seattle for first place in the Western Conference, ended a five-game winning streak but moved to 10-2-3 since the World Cup break in June.
Di Vaio finished a four-pass attack on the rush to open the scoring in the 28th minute. Piatti got a pass back from Dilly Duka and slipped the ball to an unmarked Di Vaio, who back-heeled in his sixth goal of the season.
Duka sent Montreal in on a three-man breakaway that saw Felipe Martins feed Piatti for the goal in the 43rd. It was the fourth goal in the past three games for the Argentine who joined the Impact as a designated player a month ago.
The Montreal defence lost its bearings when veteran Ferrari was substituted by Wandrille Lefevre at the intermission.
A pretty diagonal pass through the penalty area by Juninho found Zardes alone at the far post to redirect his 15th of the season home in the 57th. It was Zardes's 14th goal in the past 16 games.
Substitute Gordon wasn't on the pitch for two minutes when he converted a Landon Donovan pass across the goal in the 64th. It was Donovan's 132nd career assist, three short of Steve Ralston's league record.
"To get a point when you're down two goals, you can't complain a lot, but on the night we weren't good," said Arena, who had to switch from a 3-5-2 to a 4-4-2 formation at half time because, "we didn't have players who are capable of making the adjustments in the back three.
"I'd like to see we have players who have a better tactical feel, but it's obvious that some of them don't. But that's my responsibility."
The Impact play again Sunday but the match that matters now is their CONCACAF Champions League game next Wednesday at home against the New York Red Bulls. Getting through the group stage could save a dismal season.
Klopas appealed to the Impact fans to pack the 20,000-seat stadium.
"It's probably our biggest game of the season and we need it," he said.
Donovan, who is to retire at the end of the season, as well as L.A.'s Dan Gargan and Montreal's Felipe all were cautioned and will miss their next game due to yellow card accumulation.
The Galaxy had Robbie Keane back from international duty, where he helped the Republic of Ireland beat Georgia in Tbilisi on Sunday.
Notes: Montreal had veteran Heath Pearce in for Lefevre at centreback and Calum Mallace replaced Patrice Bernier in midfield. Bernier, Issey Nakajima-Farran, Ouimette and Jeremy Gagnon-Lapare had all had been with the national team. . . It was the Galaxy's first game at Saputo Stadium. In 2012 they played to a 1-1 draw at Olympic Stadium.