Back-to-back wins have seen the visitors move within four points of the top seven in the Eastern Conference, while their hosts sit 10th in the Western division but just a single point outside of the playoff places.
Match preview
Vancouver Whitecaps had to battle through a particularly tough start to the new MLS campaign, as they amassed just four points from their opening eight games.
Vanni Sartini's side then displayed an impressive turnaround, though, winning six of their next 10 matches and collecting 20 points from a possible 30 to put themselves in a stronger position in the fight for playoff places.
The final win of that run - an impressive 1-0 victory over Conference leaders Los Angeles FC thanks to Andres Cubas's 89th-minute goal - was then followed by a 3-1 defeat at the hands of Minnesota United, despite taking a lead through Lucas Cavallini, as Kemar Lawrence, Luis Amarilla and Franco Fragapane turned the game on its head with goals in the final 20 minutes.
In their bid to return to winning ways, The Village took on FC Cincinnati but were only able to take a point thanks to Cristian Dajome's late leveller, before being pegged back and forced to settle for a share of the spoils away at Portland Timbers last time out, as Felipe Mora drew their opponents level in the 82nd minute after Brian White had put Vancouver ahead.
Having now put themselves in the playoff race thanks to their impressive form in recent months, Sartini's men will aim to put an end to a three-game winless run on Sunday and climb into the top seven with what would be an eighth three-point haul of the term.
They meet a Chicago Fire side hoping to build on consecutive wins and climb closer to the top seven after a tough start of their own.
Following an unbeaten first five games, Ezra Hendrickson's side had to endure a dismal run of form, going without a victory for their next 10 outings and picking up just three points along the way.
Sitting towards the foot of the Eastern Conference and in need of a change in fortunes, the Illinois outfit were, at least, able to pick up wins over DC United and Philadelphia Union in a three-match span at the end of June, before suffering another setback with back-to-back defeats at the hands of San Jose Earthquakes and Columbus Crew.
Hendrickson's men now look to have put their struggles behind them, though, firstly following those losses up with a 2-0 beating of Toronto FC, thanks to Jhon Duran's early brace, before Rafael Czichos fired them to a 1-0 victory over Seattle Sounders on home turf.
Now sitting 12th in the Eastern Conference, four points outside of the top seven, Chicago Fire will look to put three straight wins together in the MLS for the first time in over four years to continue their climb towards the playoff places after their tough spell.
Vancouver Whitecaps Major League Soccer form:
Vancouver Whitecaps form (all competitions):
Chicago Fire Major League Soccer form:
Team News
Vancouver Whitecaps goalkeeper Cody Cropper was forced off through injury in their game against FC Cincinnati, and, with regular stopper Thomas Hasal, 20-year-old Isaac Boehmer will have to deputise from the start.
Canadian international Lucas Cavallini should continue to lead the line, having hit six MLS goals so far this season.
Ryan Gauld has been another important man going forward since his arrival from SC Farense, with the creative midfielder adding to his goals tally last time out, and he should again support the lone striker.
Ezra Hendrickson could deploy an unchanged Chicago Fire starting XI after their second straight victory last time out, with Carlos Teran and Rafael Czichos bound to continue their partnership at the heart of the back four.
Front man Kacper Przybylko has struggled to carry his MLS scoring form from recent years into this campaign with his new side, having only netted three league goals thus far, but he should again be trusted to lead the line.
The lone striker will be supported by former Liverpool, Inter Milan and Lyon star Xherdan Shaqiri, who has already chipped in with three goals and two assists from midfield.
Vancouver Whitecaps possible starting lineup:
Boehmer; Brown, Godoy, Blackmon; Raposo, Teibert, Jungwirth, Dajome; Gauld, Vite; Cavallini
Chicago Fire possible starting lineup:
Slonina; Sekulic, Teran, Czichos, Bornstein; Gimenez, Navarro; Mueller, Shaqiri, Gutierrez; Przybylko