Phoenix Mercury guard Kahleah Copper, the team's top scorer last season, underwent a left knee arthroscopy and will be sidelined for four to six weeks.

The Mercury announced Copper's status before the team's season-opening 81-59 win over the Seattle Storm on Saturday. The team also said forward/center Natasha Mack would miss two to three weeks with a lower back injury.

Both players had already been ruled out for the opener and were previously listed as day-to-day.

A nine-year veteran, Copper, 30, was the WNBA's third-leading scorer last season, averaging 21.1 points per game in her first season with the Mercury, trailing only Las Vegas Aces center A'ja Wilson's 26.9 and Dallas Wings guard Arike Ogunbowale's 22.2.

Copper was expected once again to be one of the Mercury's top contributors this season, especially with the retirement of Diana Taurasi and the departures of Brittney Griner, Natasha Cloud and Sophie Cunningham.

Satou Sabally and Alyssa Thomas, two of the team's key offseason additions, combined for 47 points in Phoenix's win Saturday.