BRIDGEVIEW, Ill. -- The theme for the Chicago Fire will not change over the next several weeks. Chicago is in must-win mode with six regular-season matches remaining. And as long as the rest of the MLS field continues to oblige by keeping the Fire in the mix, that outside chance of a postseason berth remains.

The Fire (5-8-15, 30 points) host the New England Revolution (5-12-12, 27 points) this Sunday at Toyota Park, facing the only team remaining on Chicago's schedule that is in worse shape than the Fire.

"Now that we've put kind of a little run together, we've got to keep it going," Fire goalkeeper Sean Johnson said. "We can't afford to take strides forward and then take steps back. We've got to keep pushing, pushing, pushing, until we get to where we want to be. And that's ultimately the playoffs."

Before Saturday night's match between the expansion Portland Timbers and the host New York Red Bulls, Portland was holding on to the final wild card berth with 37 points -- one point ahead of New York. Also heading into Saturday, the Fire were seven points behind the Timbers.

The Fire have won three of their past four matches, and Chicago's offense has been energized by the play of forward Dominic Oduro.

Oduro has been on a tear over the past month and a half, most recently notching a shorthanded, game-winning tally against Chivas USA last Saturday to up his season total to 10 goals. He became the first Fire player since Damani Ralph in 2004 to reach double digits. Oduro is now in the running for the Golden Boot, thanks to five goals over Chicago's past seven regular-season matches.

Defensively, Fire center back Cory Gibbs was issued a red card during Chicago's win over Chivas and will miss Sunday's match. Chicago right back Dan Gargan will be back in the fold after missing the Chivas match (yellow card accumulation).

Chicago has allowed four goals in its past two games, and the Fire will have to play again without a key defensive component in Gibbs. The Fire's back line has had to reconfigure itself every week, dating back to left back Gonzalo Segares missing the Sept. 10 loss to the San Jose Earthquakes (yellow card accumulation).

"When you change formations it's always difficult getting guys on the same page," Johnson said of the recent defensive adjustments. "No matter what team's on the field, I think everyone is capable of getting the job done."

Chicago's three victories over the past month have all come at home. The Fire have improved their Toyota Park record to 4-2-8.

The Revs are on the edge of elimination from postseason contention, and a loss to the Fire would surely represent the end to their season.

New England was dealt a significant hit up front when Danish striker Rajko Lekic sprained his left ankle during the team's 3-0 loss to the Timbers last Friday. Lekic, who is second on the team with six goals, is expected to miss most of the Revs' remaining games -- if not all of them.

Lekic helped New England salvage a 1-1 draw when the Revolution faced the Fire on June 18 at Gillette Stadium. Chicago had a 1-0 halftime lead thanks to an Oduro goal in the 32nd minute. But shortly after the break in the 48th, Lekic tallied the equalizer to come away with a point at home.

Lekic's presence will be sorely missed as midfielder Shalrie Joseph represents the only big offensive threat to date. Joseph has provided 25 percent of the Revs' scoring this season with a team-leading eight goals.