After dropping Game 1 of the WNBA semifinals, 91-87, to the Seattle Storm on Sunday, the Mercury are facing a critical Game 2 on Tuesday at KeyArena.

Mercury head coach Sandy Brondello knows her team is up against a challenge in a deep Storm squad that features league MVP Breanna Stewart, who scored a game-high 28 points in Sunday’s game.

The Storm successfully executed a double team on Mercury forward Brittney Griner, a two-time WNBA Defensive Player of the Year, and broke off a 16-4 run in the third quarter en route to a win.

Brondello said the Mercury will have to adjust their game plan on Tuesday.

“(Brittney) needs to try and get more high-and-low action so they can’t bring the trap,” Brondello said. “Her just getting two feet in the paint so it’s a little bit easier. There’s things that we’ll put in place; we’ll put her in more pick-and-rolls as well. Hopefully we can get her going and get her some more quality looks.”

Brondello pointed to unforced turnovers and a lack of discipline to start the second half as a reason the Mercury fell into a sizable hole in the third quarter, in addition to allowing too many uncontested shots.

And although the Mercury made it a 2-point game with 1:40 left in regulation, the second-half turnovers were still an “achilles heel” that the team will need to clean up ahead of Tuesday’s game, Brondello said.

“They’re a great team,” Brondello said of the Storm. “We had a good game but we didn’t have one our great games. Especially in the first half, we allowed Breanna to get too many open looks and too many open threes. … Still, we only lost by 4 so we’ve got to take some positives in that it was a close game and we fought hard in the fourth.

“We know we’ve got to get better, and particularly in the defensive end, if we want to come out here and steal one from Seattle.”

The Mercury can still take positives from Sunday’s game given how they played during their last regular-season meeting with the Storm on July 31, an 11-point defeat in Phoenix in which the Mercury got “smashed,” as Brondello put it.

Brondello said the Storm caught the Mercury at a time when the team was struggling to find its rhythm after the All-Star break. Since then, the biggest change has been the increased role of forward DeWanna Bonner.

Bonner has been one of the Mercury’s top scorers since Sancho Lyttle tore her ACL in early July, a trend that has continued in the playoffs. Bonner ranks second among active players with average of 26.3 points per game to go along with 14 rebounds per contest.

The emergence of Bonner has turned the Mercury into a team that Brondello sees as a better rebounding and defensive team.

“She’s doing everything, really,” Brondello said of Bonner. “Her size and ability allow her to go get the ball and she’s been a huge asset for us. They have to respect her because she can shoot deep threes but also play off the dribble. She cuts well, reads defenses well and finishes at the rim.

“She’s got the total package and can be a great defender when she gets locked in, too. She really has improved. She was always a good player but I think she’s gone to another level. She’s really shown how valuable she is to our success.”

On Tuesday, the atmosphere will be more intense than it has been all season. Brondello knows the Mercury will have to answer the call.

“We’re ready for the challenge,” Brondello said. “We know we’re right there but we have to limit some of our unforced turnovers and mistakes on defense. We’re a much better team than what we were.”

Tuesday’s game

Game 2 – Phoenix Mercury at Seatle Storm

When: 7 p.m. | Mercury schedule | WNBA playoff bracket

Where: KeyArena, Seattle

TV: ESPN2

Streaming: Watch ESPN app

Outlook: The Mercury will look to bounce back from a Game 1 loss in an attempt to even up the best-of-five series against the Storm in Seattle. … Phoenix was down just 2 points with 1:40 left in the game, but a 16-4 run in the third quarter by Seattle proved insurmountable. … Prior to Sunday’s game, Storm guard Breanna Stewart was named the league’s MVP. She led all scorers in Game 1 with 28 points. … DeWanna Bonner and Diana Taurasi of the Mercury finished with 27 and 25 points, respectively. … Taurasi, who finished fifth in the MVP voting, was called for a technical foul in the first half. …The Mercury host Game 3 on Friday and possibly a Game 4 on Sunday.