– In retrospect, it was a bomb that reverberated all through a suddenly loud US Airways Center.

It was as improbable as it was incredible. And, maybe, it was the key blow in a game that, up to that point, had been a gutty example of give and take.

For at least this season, the Lynx’s reign is over, thanks to the Phoenix Mercury in a 96-78 victory Tuesday.

The Mercury won the best-of-three WNBA Western Conference finals, ending a three-year run in which the Lynx had reached the league finals.

“We wanted a chance to defend our title, but it just didn’t work out for us,” Lynx coach Cheryl Reeve said.

It was Mercury guard Diana Taurasi who led the way and lit the fuse.

Down 10 points in the third quarter, the Lynx clawed back into the game behind Seimone Augustus. She had eight points in a 13-3 run that tied the score 67-67 on Maya Moore’s driving layup late in the quarter.

Enter Taurasi.

She hit a jumper at the other end. Then, after a Lynx turnover with two seconds left in the quarter — Lindsay Whalen was called for traveling, a call the Lynx hotly protested — Taurasi took an inbounds pass and launched a nothing-but-net heave from at least 50 feet that, in retrospect, might have given the Lynx shellshock.

“When anyone makes a shot like that,” said Mercury coach Sandy Brondello, “You think, ‘OK, it’s our night.’ To me, she’s the best player in the world.”

Or, viewed from the other side: “That was probably our breaking point,” Augustus said. “Something like that happens, after we tied the game, it was almost like a backbreaker. We never rebounded from that.”

Because this is what happened: Those five points from Taurasi were just the beginning. She came out and scored the first eight points of the fourth quarter. By the time the Lynx finally scored — on a Whalen driving layup with 4:23 left — the game was out of hand.

“There’s always plays in games that turn the tide,” Taurasi said. “For the most part, going into the last couple minutes of the third, they got the momentum. A couple plays turned that.”

The Lynx were outscored 24-11 in the fourth quarter. Go back to the final moments of the third quarter and that run was 29-11.

And the game was basically over. As the minutes ticked away, Reeve was assessed two technical fouls and was escorted from the court as the crowd roared.

“I was hoping to be able to congratulate Sandy on the court, about how well her team played,” Reeve said. “I thought Phoenix played great. They were hard to play against. It wasn’t like we played bad. I have a good team.”

But, ultimately, the Lynx couldn’t stop the Mercury. Taurasi had 31 points, hitting 12 of 17 shots to go along with seven assists and five rebounds. Brittney Griner added 22 points, DeWanna Bonner and Candice Dupree had 14 each and Penny Taylor 10.

The Mercury shot 58.7 percent from the field, scoring 56 of its points in the paint as the Lynx struggled to contain Griner and defend the pick-and-roll.

But before that turning point, the Lynx had been game.

With the big three of Augustus (21 points), Whalen (20) and Moore (16) leading the way, the Lynx came all the way back from 10 down to tie the game.

Only to see it slip away.

“We stopped scoring,” Reeve said. “Phoenix was really hard to stop. In order to have a chance to beat ’em, you have to score.”

Ultimately, relying too much on only three players hurt the Lynx, who didn’t get enough scoring elsewhere.

“We overcame so much this season,” Moore said. “We always believed we have it in us to overcome things, overcome runs. Just not enough this time.”