The Impact (6-18-9), who are last among Major League Soccer's 19 teams, take on D.C. United (17-9-7) at Saputo Stadium on Saturday afternoon.
D.C. finished at the bottom of MLS last season with a dreadful 3-24-7 record, but after a few wise player moves will finish first in the Eastern Conference and have the top seed going into the playoffs. The Impact hope for the same kind of turnaround in 2015.
"It's not the first time that's happened in this league," said Impact midfielder Patrice Bernier. "You can take some positives from that.
"You can say, this was an 'oops' in the history of the club and that next year it will turn around. This team should have done better, but there are seasons like that. If you look at D.C. United, they managed to psychologically turn it around and become a top team in the league."
The Impact will also make changes, although coach Frank Klopas said the team needs to evaluate what it has, what is available and where they stand in terms of the league salary cap before they decide who to go after.
"We need to look at areas we can improve the team," said Klopas. "Those decisions aren't always easy, but you have to try to make this team better.
"But I also believe in bringing the right guys here so we can have continuity instead of bringing in new players every year. We brought a guy like (Ignacio) Piatti in late in the season and we made some changes that have made the team better. We need to make some moves."
One will be finding a replacement for Di Vaio, perhaps the best player the Montreal Impact have ever had.
It will be the final game of the former Italian Serie A forward's 20-year career. The 38-year-old is to be given a sendoff in a pre-game ceremony to be attended by his boyhood friend and former Impact and Italy teammate Alessandro Nesta, who had his retirement game at the end of last season.
Di Vaio joined Montreal three months into its MLS expansion season in 2012 and became a fan favourite and the club's top offensive weapon. His intensity as well as his high skill level were evident from his first season.
"There's going to be a lot of emotions for me, for my family, for everybody here," Di Vaio said Friday. "It's going to be a nice day for us, but it isn't easy."
Upon retirement, Di Vaio is expected to take a job with his last Italian club Bologna, which was recently bought by a group that includes Impact president and owner Joey Saputo.
"I prefer thinking about this moment now," he said. "On Sunday, I'll think about my future.
"For now the most important thing is to close one door, and then maybe open another one for my life."
Di Vaio will be missed, both for the 33 goals he has scored in 75 MLS games, the prestige he brought to the club and the professional attitude he took into the locker room.
"When he signed, more people paid attention to the Montreal Impact," said Bernier. "In this league, it's been Thierry Henry and David Beckham but that was in L.A. or New York. Now, outside of MLS, people were talking about the Impact.
"It's going to be a bit sad to be on the field. He was the first guy I'd look for when I had the ball and he's my neighbour in the locker-room. His 2013 season (20 goals) was fantastic. Everybody has some sort of memory of the goals he scored."
Di Vaio will not be available when the Impact play in the quarter-finals of the CONCACAF Champions League against Mexican club Pachuca in February and March.
With Sporting Kansas City's loss to Costa Rica's Saprissa on Thursday night, the Impact finished the group stage as the fourth seed with a 3-0-1 record while Pachuca is seeded fifth. They had hoped to draw an MLS team because Mexican and Central American clubs will be in mid-season form in February while they will still be in training camp.
Klopas said his team will need to put extra emphasis in off-season fitness and preparation to be ready for Pachuca.
"It's a team with a lot of history,"he said. "You could say it's better to play an MLS team because they're in the same boat as us, but at the same time, it's exciting for our fans to see a different team.
"The positive thing is we finished first in our group."
D.C. United went 4-0-0 and is the top seed for the quarter-finals.
The Impact will be short three veteran defenders for their season finale, as Matteo Ferrari, Hassoun Camara and Heath Pearce are all suspended for one game. Piatti will also sit out due to knee tendinitis.
This will leave Montreal with an inexperienced back line likely to include academy products Wandrille Lefevre and Karl Ouimette as well as rookie Eric Miller along with Kzryztof Krol and second-string back Futty Danso.
Goalkeeper Evan Bush said it's a chance for the young players to shine.
"They are familiar faces, I see these guys every day, but maybe guys who haven't got much playing time throughout the year," said Bush. "We have three suspensions, maybe an injury or two also on the back line to deal with, but it's the time of the year when guys get chances.
"Hopefully they're ready to step on the field and contribute. I think they will be."
D.C., which has first place locked up, may opt to rest players for the post-season.