SEATTLE, Sept. 15 (Ticker) -- The Phoenix Mercury are piling up losses at the worst time of the year.

Led by Lauren Jackson's game-high 25 points, the Seattle Storm handed the Mercury their third loss in a row, with a 73-58 victory.

NBA TV highlights from Mercury-Storm: 56k | 300k

The loss drops Phoenix to .500 (16-16) and cuts its lead over the Sacramento Monarchs for the fourth and final playoff spot in the Western Conference to one-half game.

The Mercury played like a team that wanted to make the playoffs for most of the first half, taking a 25-12 lead on a 3-pointer by Diana Taurasi with 5:33 to go. However, the Storm finished the half on a 15-5 run to make the score 30-27 at the half.

Taurasi, who led Phoenix with 20 points, buried a 10-footer to give the Mercury a 40-37 lead, but Tully Bevilaqua tied the game with a 3-pointer that kicked off a 25-7 run by Seattle.

Jackson, the reigning Most Valuable Player, led the charge with 14 points in the second half for the Storm, who are already locked into the second seed in the Western Conference in the upcoming playoffs.

The Mercury have two games remaining while the Monarchs have three left, and hold the tiebreaker by virtue of winning the season series.