Stewart scored 19 of her 28 points in the first half, Jewell Loyd added 23 - including Seattle's final seven points - and the Storm held on to beat the Phoenix Mercury 91-87 on Sunday in Game 1 of their WNBA semifinal series.
Stewart was the star for the first 20 minutes, but it was Loyd that hit the shots Seattle needed to hold off Phoenix's fourth-quarter rally.
''Anyone can score, anyone can get it going and tonight you had a glimpse of everyone stepping up and getting it going for us,'' Loyd said.
After posting the best record in the league during the regular season, Seattle got a week of rest before opening the semifinals at home. For the most part there was no rust from the long layoff, but Phoenix made the final minutes uncomfortable after cutting a 16-point deficit to two.
Loyd came up with a pair of clutch baskets, including a 15-footer with 1 minute left to beat the shot clock and pushed Seattle's lead to four. It came on a second-chance opportunity after Stewart chased down an offensive rebound that led to Loyd's key shot.
''We didn't stop. We didn't freeze when things got tight,'' Stewart said. ''Playing Phoenix you always know they're in the game no matter what, whether it's a two-point game or a 10-point game they have an opportunity to come back and win. We made some hustle plays that gave us multiple possessions.''
DeWanna Bonner led Phoenix with 27 points and 13 rebounds, and Diana Taurasi added 25 points. But the third of Phoenix's big three stars, Brittney Griner, was held to 13 points and battled foul trouble throughout.
Phoenix opened the playoff with a win at home over Dallas before traveling cross country to knock out Connecticut, and taking another cross country trip to Seattle to open the semifinals. If there was any fatigue, Phoenix didn't show it in the fourth quarter, outscoring Seattle 20-12 and making for a tense final minute.
''We just showed a lot of fight and poise, which we probably didn't see much of that throughout that game like we needed, starting with me,'' Taurasi said.
Seattle led by 70-54 after Stewart's sixth 3-pointer midway through the third quarter, but Phoenix had a fourth-quarter surge waiting. Stewart scored on the low block with 4:57 left to push Seattle's lead back to 10. Phoenix responded with a 13-5 surge led by Taurasi. She followed up a deep 3-pointer with a pass to a cutting Bonner for a basket. Stewart missed twice near the basket on Seattle's next possession and Griner's second-chance basket with 1:40 remaining pulled the Mercury within 89-87.
Alysha Clark missed an open 3 for Seattle, but Stewart's offensive rebound led to Loyd's 15-footer that barely beat the shot clock to push Seattle's lead to four.
Taurasi became the WNBA's all-time leader in playoff scoring, passing Tamika Catchings. Taurasi needed just eight points entering the game. ... Seattle improved to 11-0 this season when Loyd scores 20 or more points. ... Hall of Famer Bill Russell continued to make the rounds of Seattle basketball this summer sitting courtside for Game 1. A week ago, Russell showed up at the popular Seattle summer pro-am league run by NBA veteran Jamal Crawford. Russell visited the Phoenix locker room after the game and received a hug from Taurasi.
Phoenix committed 16 turnovers Seattle was able to turn into 22 points. Phoenix had just eight and 10 turnovers in each of its first two playoff games.
Along with Stewart becoming the second Seattle player to be named MVP, Howard was named the league's most improved player and Bird received the 2018 Kim Perrot Sportsmanship Award. It's the third time in her career Bird has received the sportsmanship award. Howard received 29 of 39 first-place votes, becoming the first Seattle player to receive the most improved honor.
Game 2 of the best-of-five series is Tuesday night in Seattle.