The Sky have a chance to erase their slim deficit Sunday night with some help and a home win over the Washington Mystics.
Delle Donne missed 17 of 18 games and 12 in a row because of recurrence of Lyme disease before returning in Thursday's visit from New York. The Sky (11-16) went 5-12 without their leading scorer and the 2013 WNBA rookie of the year.
Delle Donne came off the bench to play 10:38 against the Liberty and scored 10 points in an 87-74 victory, her club's third in the last 11 games.
"It's just awesome to be back with the team competing," said Delle Donne, who was 3 for 8 from the field. "I feel really good and I'm happy we were able to keep the minutes down because it's something I'm going to have to build on."
Completing a season sweep of New York put Chicago just a half-game behind the fourth-place Liberty with seven to play. New York, which has a game in hand, visits East-leading Atlanta on Sunday.
"Every game from here on out is a must win," said center Sylvia Fowles, who had 16 points and 14 rebounds. ''We have to stay on our toes, continue to be aggressive and do the things we haven't done all season to make it into the playoffs."
The Sky played without Delle Donne in each of their two losses to Washington this season. They also didn't have Fowles (hip) and starting forward Jessica Breland (shin) in a 79-68 road defeat June 13.
Starting guard Courtney Vandersloot missed a 72-65 loss July 9, which snapped Chicago's seven-game home win streak over the Mystics. Vandersloot has sat out the past 12 games because of a sprained left MCL and is expected to miss an additional two weeks.
The Mystics (13-14) head into Chicago after having a season-best, four-game win streak snapped Tuesday with an 80-76 overtime loss at New York. They rallied from a 15-point deficit in the third quarter before suffering just their second defeat in eight games.
Kia Vaughn had 12 points after scoring a combined 14 in her prior three games, and 12 rebounds, one shy of her career high.
Washington owns a two-game lead on a playoff spot with seven to play, and coach Mike Thibault is hopeful his team doesn't have to absorb many more difficult lessons in a competitive East race.
"I hope we learn from it, if we lose this game and learn from it and it makes us better, great," he said. "If it doesn't make us smarter, it's a waste."
The Mystics and Sky conclude their season series Aug. 13 in Washington.