LAS VEGAS (AP) -- Kelsey Plum scored 20 of her 25 points in the second half, and the Las Vegas Aces beat the Phoenix Mercury 96-90 on Tuesday night in Game 1 of the WNBA semifinals.

Plum, the fourth-year guard who won an Olympic gold medal in 3-on-3 basketball, had 12 points in the third quarter as Las Vegas pushed its lead into double digits.

Riquna Williams scored 24 points for the Aces, who will host Game 2 on Thursday.

Phoenix, which won single-elimination games against the New York Liberty and defending champion Seattle Storm to reach the semis, led 30-21 after the first quarter.

Brittney Griner had 24 points, seven rebounds and six assists for Phoenix. Diana Taurasi, playing in her second game since returning to the lineup after sustaining a sprained ankle, scored 20 points on 6-of-17 shooting.

Williams scored 14 points in the opening 10 minutes to keep it close.

The Aces shot 56% (14 of 25) in the second to take a 52-49 lead at halftime. Las Vegas took its first lead with 4:05 left in the first half on a 3-pointer from Plum.

A'ja Wilson finished with 15 points and eight rebounds. She had a personal 6-0 run to push an 85-81 lead to 10 points with 3:08 remaining.