Elena Delle Donne led four Chicago players in double figures with 22 points, as the Sky downed the Washington Mystics, 93-79, on Sunday at Verizon Center.
Delle Donne added seven rebounds and five assists, while Epiphanny Prince went 5-for-5 from 3-point range en route to 21 points for the Sky, who have already secured the top seed in the Eastern Conference.
Ivory Latta netted a team-high 18 points to go with seven rebounds for the Mystics, who were looking to secure their first Eastern Conference playoff berth since 2010.
With just three games remaining, Washington holds a three-game lead over New York for the fourth and final playoff spot in the East. The Mystics visit the Liberty in their final game of the season.
Washington trailed for much of the contest, but got within five early in the fourth before Chicago ripped off eight straight points to push the margin to double-digits.
A Prince 3-pointer with 3:29 left extended Chicago's lead to 85-68 and the Mystics failed to threaten the rest of the way.