The Seattle Storm opened their first-round playoff series against the two-time defending champion Las Vegas Aces -- a 78-67 loss -- without starting center Ezi Magbegor.
Magbegor was ruled out of Game 1 on Sunday because of a concussion that forced her to miss the final three games of the regular season. She suffered the injury in a Sept. 13 win over the Dallas Wings.
The Storm have not given a timeline for Magbegor's return.
Magbegor, 25, is considered one of the top defenders in the league, making the all-defensive second team the past two seasons. She was the anchor of a team that led the WNBA in blocks, with her 2.2 blocks per game ranking second this season to Aces star A'ja Wilson.
A five-year veteran, Magbegor averaged 11.7 points and 8.0 rebounds.