Trevor Ruszkowski-USA TODAY Sports

Sabrina Ionescu scored 20 of her 29 points in the second half as the second-seeded New York Liberty shook off a sluggish start and beat the visiting Washington Mystics 90-75 on Friday in Game 1 of a first-round playoff series.

The Liberty can clinch the best-of-three set with a win Tuesday night on their home court thanks to Ionescu's stellar showing in her fifth career playoff game.

Ionescu made 10 of 18 shots and set a New York playoff record by sinking seven treys on 13 attempts. The guard made six of her 3-pointers after halftime and four in the fourth quarter to help New York maintain enough separation. Her point total was personal high in a postseason game.

Jonquel Jones collected 20 points and 12 rebounds and Betnijah Laney added 14 of her 19 points in the opening half as the Liberty shot 44 percent and withstood a quiet showing from Breanna Stewart.

After struggling in the regular season against Washington, Stewart was held to 10 points on 3-of-16 shooting and missed all four of her 3-point tries.

Myisha Hines-Allen scored 21 points to lead the seventh-seeded Mystics, who led by six after the opening quarter. Brittney Sykes added 16 and Ariel Atkins contributed 14, but Natasha Cloud was held to four points on 1-of-8 shooting. The Mystics hit 41.3 percent from the floor and missed 17 of 22 3-point tries.

Washington shot 57.1 percent in the first quarter and held Stewart scoreless on 0-of-4 shooting to take a 29-23 lead after Tianna Hawkins canned a 3-pointer with three seconds left.

Two free throws by Stewart with 7:25 remaining in the half gave New York its first lead at 30-29. Stewart scored her first basket by hitting a layup with 58.1 seconds left and the Liberty held a 46-42 lead at halftime when Laney beat the buzzer with a layup.

After a basket by Hines-Allen got Washington within 50-48 in the third quarter, the Liberty scored the next 10 points and took a 12-point edge on two free throws by Jones with 3:27 remaining in the third.

New York took a 69-57 lead into the fourth when Ionescu hit a 3-pointer with 38 seconds left and sank a short jumper right before the buzzer.

Washington got within 71-65 on a three-point play by Sykes with 8:02 remaining, but Ionescu hit consecutive treys for a 77-65 edge with 6:43 remaining. Laney sank a 3-pointer less than a minute later to make it 80-67, and Ionescu hit another trey with 2:34 left to ice it.

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