The Mystics will face second-seeded Atlanta in a three-game conference semifinal series.
New York (11-19) now trails fourth-place Indiana by three games with four games to play.
New York got off to a slow start, trailing 23-13 after the first quarter. The Sparks led 39-30 at halftime.
Cappie Pondexter scored 18 points to lead New York (5-7), which has lost five of its last six games.
The Liberty had three chances after Johnson’s go-ahead basket, but Katie Smith missed two three pointers, and Pondexter missed another shot.
Cappie Pondexter and Plenette Pierson scored 17 points, leading the Liberty past Atlanta 76-67 for the Dream’s first loss this season.
Liberty coach Bill Laimbeer says he plans to start veteran forward Katie Smith in Carson’s place and rookie Toni Young could see more playing time.
Before they were college basketball stars and the future of the WNBA, Brittney Griner, Skylar Diggins and Elena Delle Donne had something else in common: They were all bullied when they were kids.
NBA Commissioner David Stern will retire in February 2014, 30 years after he took charge of the league. He will be replaced by Deputy Commissioner Adam Silver.
New York Liberty defeated the Tulsa Shock, 91-74, on Saturday at the Prudential Center, closing out the regular season for the home team.
The WNBA’s Connecticut Sun is celebrating its 10th season by naming an all-decade team.
Trailing by nine points with about nine minutes remaining, a loss to last place Washington could have dealt a serious blow to the New York Liberty’s playoff chances.
Tina Charles had 23 points and nine rebounds to lead the Connecticut Sun to an 85-74 victory over the New York Liberty on Saturday night.
The American women captured their fifth-consecutive Gold Medal at the Olympics by defeating France, 86-50.
The San Antonio Silver Stars beat the New York Liberty 94-81 Sunday.