With the first playoff win in franchise history secured, the Chicago Sky find themselves in a great spot to reach the Eastern Conference finals.
The Atlanta Dream, meanwhile, are fighting for one more game at home.
After stealing home-court advantage with a hard-fought win over the top-seeded Dream, the Sky return home Sunday night with a chance to clinch the best-of-three series.
Chicago went into Friday's opener with a 6-11 road record and had dropped two of three in Atlanta during the regular season, including a 97-59 loss June 7 that was by far its most lopsided defeat of the year.
The Sky played that contest without Sylvia Fowles, while Elena Delle Donne struggled through a 3-for-10 shooting performance in her final game before being sidelined for an extended period by a flareup of Lyme disease.
Both players are finally healthy and were in the starting lineup for Game 1, though it was Courtney Vandersloot who provided the heroics by hitting a tiebreaking jumper with 20 seconds left and later adding a free throw to lift the Sky to an 80-77 victory.
Delle Donne and Fowles did most of the heavy lifting. Delle Donne scored 21 points, while Fowles added 12 points and 14 rebounds. Epiphanny Prince scored 14, Vandersloot had 13 and Tamera Young 12 to put the entire starting five in double figures.
Chicago trailed 35-23 with 4:24 left in the second quarter before settling down and focusing on defense. The Sky forced Atlanta to miss seven of its final eight shots in the quarter and limited the up-tempo Dream to two fast-break points in the game.
"We had 10 deflections in that (second) quarter, and when we get deflections, we're a phenomenal team," said Delle Donne. "I really feel like we slowed down, calmed down and executed. We were a little crazy at first."
Angel McCoughtry scored 24 points but was 8 of 22 from the field for Atlanta, which went ahead 77-75 with 1:40 remaining. Sancho Lyttle had 14 rebounds but shot 3 of 15 and finished with six points. Erika de Souza scored 12.
Now the Dream will have to end a four-game losing streak in Chicago to force a decisive Game 3 at home Tuesday. Atlanta's most recent win in the Windy City came in September 2012.
"I was always told by a former coach of mine, Pat Riley, that championships are won on the road," said coach Michael Cooper, a former guard for the Los Angeles Lakers. "I think the pressure now switches to them to close us out Sunday so we're going to go there and give them a good fight, and try to get this (back) to Atlanta."