SEATTLE -- Breanna Stewart scored 18 points, Kaleena Mosqueda-Lewis added 16 and the Seattle Storm clinched the seventh seed in the WNBA playoffs with an 88-75 victory over the Chicago Sky on Sunday night.

Seattle will play at Atlanta in the opening round of the playoffs. Stewart also grabbed 11 rebounds, including her 277th defensive one of the season to pass Lisa Leslie's WNBA record of 276 set in 2004.

The Storm had just a 63-61 lead at the end of the third after Allie Quigley hit Chicago's first 3-pointer of the game with 1.3 seconds left in the quarter. But Mosqueda-Lewis made back-to-back 3-pointers and Stewart added another 3 as Seattle opened the fourth on a 16-2 run to take a 79-63 lead much to the delight of the 12,186 fans. Chicago only scored six points through the first eight minutes of the fourth.

Sue Bird had 14 points and five assists for Seattle (16-18). The Storm needed to win to secure the seed after Phoenix beat the San Antonio Stars earlier. The Mercury will be the No. 8 seed.

Stewart made two free throws early in the third quart to pass Candace Parker for third place on the WNBA's rookie scoring list. She has scored 621 points and only trails Seimone Augustus (744) and Cappie Pondexter (624).

Jamierra Faulkner and Jessica Breland each scored 14 points for Chicago (18-16). The Sky played without star Elena Delle Donne for a fifth straight game.