The Chicago Sky are in the WNBA playoffs and the Mercury can join them with a victory in the teams' regular-season finale on Sunday in Phoenix.
The defending champion Sky (25-10) currently reside in second place, however they could elevate to the No. 1 seed with a win and a Las Vegas Aces' loss to the Seattle Storm on Sunday.
The seventh-place Mercury (15-20) are tied with the New York Liberty, with both the Minnesota Lynx and Atlanta Dream one game back. Phoenix aided its cause with an 86-74 victory over the Dallas Wings on Friday. The top eight teams in the overall standings advance to the postseason.
"You've got to control what you've got to control and we knew that coming into the game (on Friday) that the only thing was just winning and taking care of business," said Diamond DeShields, who scored 24 points against the Wings.
Phoenix won despite playing without Diana Taurasi (quadriceps), who also will miss Sunday's game.
"This is an extremely resilient group," Mercury coach Vanessa Nygaard said. "We couldn't count on anything this season to go our way at any moment. We can only count on us. That's what we saw."
The Sky slipped from the top seed after an 89-78 loss at Las Vegas on Thursday.
"We know that we can do better," Chicago forward Emma Meesseman said. "We'll talk about this game and what we have to do better and we'll find solutions. We know we're going to be better in the playoffs."
Chicago made just 3 of 21 shots from 3-point range and scored fewer than 20 points in three separate quarters.
"That's not us," said Kahleah Copper, who scored a game-high 28 points for the Sky. "We're (No. 2) right now but we still have an opportunity to be first, so it's on to the next one and take care of the business and hope for the best."