Column: Once poised for a third-round knockout, Kings are now on the ropes

Now, the Kings know how they made the San Jose Sharks feel after the first round of the playoffs and the regrets they left the Ducks to brood over just a couple of weeks ago, in the second round.

The Kings, who staged an epic comeback after losing their first three games to the Sharks and won their last two games against the Ducks to reach the Western Conference finals, are now on the other side of the playoff fence.

Instead of coming from behind to win, they’ve lost their advantage after being ahead. Given two chances to subdue the defending Stanley Cup champion Chicago Blackhawks and advance to the Cup Final, the Kings instead squandered third-period leads in two straight games, the latest a 4-3 loss Friday at Staples Center in what might have been their last home game this season.

Now they’ll play a Game 7 on Sunday at the United Center, where the Blackhawks are 8-1 in postseason play this spring. To advance to the Cup Final against the New York Rangers, the Kings will have to become the first NHL team to win three Game 7s along the way, following their decisive seventh-game wins in San Jose and Anaheim.

How will this be different?

“Just the third round and a better opponent,” Kings Coach Darryl Sutter said.

Yeah, that’s all. The Kings have more mileage on their legs and must face a team that is finding its stride and riding the brilliant clutch play of winger Patrick Kane, who followed his four-assist performance in Game 5 by setting up the tying goal and scoring the winner Friday.

Just a round later and an opponent that’s showing as much resilience as the Kings did in defeating the Sharks and Ducks and building a 3-1 series lead against the Blackhawks.

This is a trip the Kings didn’t want to make. And for a few moments, after Alec Martinez put them ahead, 3-2, at 7:38 of the third period, it appeared they wouldn’t have to pack their bags yet again. But their inability to stop Kane — again — has put them on the edge of a playoff precipice.

“We’ve got a one-game playoff here in their building to punch a ticket to the finals,” Martinez said, “and we’ve got to focus on learning from our mistakes tonight and going in there ready to play.”

Defenseman Drew Doughty, every bit as dazzling for the Kings on Friday as Kane was for Chicago, tried to put a positive spin on the situation.

“I think before the series if we were asked ‘would you go to Game 7 with Chicago and just be put in that spot in just a one-game thing,’ I think we would take it,” he said.

But there’s a different feeling to it now, after they’ve backed into this winner-goes-to-the-finals scenario.

They haven’t been able to dictate the style in the last two outings and the Blackhawks have gained control and confidence. There’s a reason why the Blackhawks won the Cup last season and are a victory away from continuing their quest to become the first repeat champion since the 1997 and 1998 Detroit Red Wings: The Blackhawks are 13-0 in Games 5 through 7 of their playoff series over the last two postseasons, a sign they know how to close things out.

Do the Kings have enough left to close this one out?

Doughty said the other day they weren’t fatigued because “your heart doesn’t get tired.” Their collective heart must measure up to the Blackhawks’ on Sunday — and even then, that might not be enough against a team that, like the Kings, knows how to win and has both the individual skill and combined will to make it happen.

“We’ve got to win. There’s no other option,” Doughty said. “I think we’re going to have our best effort of the series next game. All the guys are going to step up to the plate. The leaders are going to lead the way, everyone else is going to follow, and we’re going to have our best effort.”

That sounded more like wishful thinking than a bold declaration of victory. But it’s their actions, not their words, that will determine whether they go home Sunday with a berth in the Stanley Cup Final or the same regrets they inflicted on the Sharks and Ducks.

helene.elliott@latimes.com

Twitter: @helenenothelen