Nneka Ogwumike had 19 points and 10 rebounds, Candace Parker had 12 points and 11 rebounds, and the Los Angeles Sparks beat San Antonio 80-67 on Saturday night.
Kristi Toliver added 15 points and seven assists for Los Angeles (21-8), which remained a game behind Minnesota for the top seed in the Western Conference.
Jia Perkins had 25 points, including 15 in the second half, for San Antonio (11-19). Jayne Appel had 10 points and 12 rebounds and Danielle Adams added 10 points.
The Silver Stars' loss clinched a playoff spot for fourth-place Seattle, which has a four-game lead over San Antonio with four games remaining for both teams, but holds the tiebreaker between the teams.
San Antonio can still catch third-place Phoenix for the West's last playoff berth. The Mercury, who host Connecticut later Saturday, began the night 4½ games ahead of the Silver Stars with seven games remaining. San Antonio, which has four games left, leads the season series 2-1 and the teams play twice more.
Ogwumike dominated early in the third with eight points, two rebounds, a block and had an assist. The assist came when she found Lindsey Harding cutting to the basket for a layup. Harding followed it with a 3-pointer that gave Los Angeles a 52-39 lead with 5 minutes remaining.
San Antonio started the game 1 for 11, with their lone basket coming on Adams' 3-pointer with 8:15 left in the first quarter.
The Sparks took a 13-4 lead following a 10-0 run keyed by a two steals and a turnover.
Parker's layup with 1:27 remaining in the first quarter put Los Angeles ahead 19-8.
The Silver Stars, who have made six straight playoff appearances, have struggled with injuries, including season-ending knee operations to All-Stars Sophia Young and Becky Hammon. Also, Danielle Robinson, named an All-Star this season, has missed the past month with a sprained right knee.