LAS VEGAS — A long, slow boil preceded Mike Thibault’s outburst.

Before the Washington Mystics’ coach and general manager finally lost his patience in the third quarter of a 92-75 blowout loss to the Las Vegas Aces on Sunday in Game 3 of the WNBA semifinals, he simmered with quiet contempt as his vaunted offense came apart with clunky possessions and inexplicable turnovers.

Officially, it was a disputed foul call on Emma Meesseman that earned Thibault a technical foul for his extended argument with the referees that required guard Natasha Cloud to step in as peacemaker.

But the Mystics, bullied all night by Las Vegas’s physical front-line combination of A’ja Wilson and Liz Cambage, spent much of the second half turning to the officials for help that never arrived. Guard Kristi Toliver took the liberty of lodging one final complaint from the postgame podium.

“[The Aces] got away with a lot of fouls," Toliver said, "and I think that makes a huge difference when in the first two games those things weren’t allowed.”

In truth, much of the Mystics’ angst was self-inflicted. Their bid to sweep through to the WNBA Finals came undone in the second quarter, when they managed just 13 points and committed eight turnovers on an uncharacteristically disjointed night.

Washington, the WNBA’s most dominant team this season, suffered its worst loss since Aug. 4. The Mystics’ league-leading offense was held to its lowest total in more than two months, as its prolific three-point attack managed to hit just 11 of its 33 attempts from outside. The bricks and clanks rained down so hard that Cloud clapped and shouted in frustration when she finally hit her first shot of the night in the fourth quarter.

“This is the first really stinker game we’ve had in a long time,” Thibault said afterward. “[The Aces] were the more desperate team.”

Washington’s pace-and-space approach exhausted and stretched Las Vegas past its breaking point in the first two games of the series. Yet the Aces returned home and countered with bruising, old-school offense and a savvy switching defense that limited the Mystics’ supporting scorers and turned Elena Delle Donne into a one-woman show.

Las Vegas, with its season on the line, also upped its energy, winning the rebounding battle 40-28 and providing energetic help defense in the paint. Washington continued to pursue its offensive goals against its physical and focused opponent, but they remained out of reach for the final three quarters.

The Mystics’ efforts to push the tempo, especially early, dwindled as they failed to get defensive stops against Cambage, who scored a game-high 28 points and grabbed six rebounds, and Wilson, who added 21 points and eight rebounds. Washington also repeatedly stopped itself. After committing 10 combined turnovers in Games 1 and 2, the Mystics committed 13 in Game 3.

“We’ve been a low-turnover team all season,” Thibault said. “The eight turnovers we had in the second quarter were not good. [The Aces] put more pressure on us, and we didn’t shoot the ball well. That was the difference.”

The Mystics’ pinpoint ball movement abandoned them during a crucial 16-2 Las Vegas run in the second quarter, as passes sailed out of bounds and bottled-up possessions died late in the shot clock. As the Aces’ lead grew in the second half, the desperate Mystics often resorted to quick three-pointers rather than patiently trusting their offense.

“We felt a little stagnant,” Delle Donne said after scoring a team-high 22 points. “We talk about having the ball move side to side. They’re a big defense. We were keeping it on one side of the floor and attacking mismatches. I think we need to move it, move it. We need to get back to the drawing board. We’ve been great all season, playing fast, in space, and we have to get back to that.”

The Aces’ defensive scheme deserves credit for containing the Mystics’ attack, at least for a night. Coach Bill Laimbeer relied more heavily on switching, a tactic that can help a defense prevent drives without leaving itself exposed to open shooters.

Although Meesseman feasted on mismatches and clean looks in Games 1 and 2, Las Vegas paid much better attention to her in Game 3. Forced to play in traffic and to contend with extra help, she finished with just six points Sunday.

“We have a series,” Laimbeer said. “We knew it was a series. We had a better bounce in our step [defensively. The Mystics] didn’t get the same number of open looks they did the past two games, especially Meesseman. She’s been standing there all by herself for five seconds before she shot the ball. Today she didn’t have those opportunities.”

There were signs of frustration from the Mystics but hardly any panic. They remain in control with a 2-1 series lead, with a potential closeout Game 4 on Tuesday in Las Vegas.

Thibault wants his team to respond with better shooting and more assertive offensive decisions. He is also seeking a tighter whistle that could help negate Las Vegas’s size advantage, lamenting that his frontcourt players were roughed up by Cambage.

The Aces center, undaunted by the complaints, pledged more of the same in an ESPN walk-off interview.

“If they can’t handle it,” Cambage said, “get in the weight room or get out of the post.”

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