Skylar Diggins-Smith will miss Phoenix's final two regular-season games due to personal reasons, putting the Mercury's playoff bid in jeopardy.
Diggins-Smith has missed the past two games and the team announced Thursday she would not play against Dallas and Chicago this week.
Diggins-Smith leads the Mercury with 19.7 points and 5.5 assists per game as they try to secure one of the final two WNBA playoff spots.
Phoenix lost former league MVP Diana Taurasi for the rest of the season to a quad strain last week and has played all year without center Brittney Griner, who has been detained on drug charges in Russia since February.
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The Mercury are tied with Minnesota, Atlanta and New York at 14-20 heading into Thursday night's games. Phoenix is vying for a 10th straight season of reaching the playoffs.