Perfect through their first nine games, the Liberty encountered their first rough patch of the season in the latter half of June.

It looked as if that would continue early in the first half of Thursday night’s home game against Los Angeles. Then a third-quarter tsunami occurred.

After trailing by 11 with 6:07 left in the third, the Liberty scored the next 13 points to take the lead. They would trail for only 18 more seconds en route to an 89-79 comeback win over the Sparks in front of 15,956 at an electric Barclays Center.

The Liberty (12-5) ended the final 5:59 of the third on a 27-6 run, including a 14-2 stretch in the last 2:59 of the quarter.

They shot 63.2% in the third, including a 5-for-7 clip from three-point range, and led 69-59 entering the fourth.

“Once we were moving, helping each other on the defensive side, our offense just came easy and that’s why we made that big run,” said Kennedy Burke, who scored 12 points on four three-pointers. “Offensively, we moved the ball. Everyone touches the ball. That’s when we get a really good shot, when we go to the second side, third side. It’s beautiful basketball, honestly.”

The Liberty scored 12 points off six third-quarter turnovers.

“Everyone kind of locked in that middle of that third, and then it was our game from there,” Natasha Cloud said.

Cloud scored 11 of her season-high 23 points in the third. Sabrina Ionescu scored 10 of her 20 in the quarter after shooting 1-for-10 and managing only three points in the first half.

Breanna Stewart had her third double-double of the season with 17 points and 14 rebounds.

“Everybody was shooting with confidence, and it opened up a lot,” Stewart said. “But really getting the stops defensively is what created all of that.”

The Liberty — who had lost two straight and five of seven entering Thursday — stretched their lead to 75-62 with 7:50 left, but the Sparks (5-13) scored the next seven points.

The Sparks cut it to 81-76 on a basket by Dearica Hamby (25 points) with 3:15 left, but Leonie Fiebich’s three-pointer with 2:27 left made it 84-76.

Ionescu made a technical free throw with 1:17 left and a bucket 14 seconds later to extend the lead to 87-76.

The 6-4 Fiebich, in her first game with the Liberty since June 10 after playing for Germany in last month’s EuroBasket tournament, had five points, three rebounds, a steal and a block in 32:38. The Liberty improved to 10-0 with Fiebich in the lineup.

The Sparks took an 11-point lead three times in the third, the latest at 53-42 with 6:07 left in the quarter. “I was proud of just how we responded,” said coach Sandy Brondello, who tied Bill Laimbeer for the second-most regular-season wins in franchise history with 92.

“We got down big, and we weren’t playing good. We were doing silly things. We just got back to being silly and not assertive. Once we turn to defense — and they take great pride in what they’re doing — the communication went to another level. We took away the easy stuff and found some momentum, and that helped us.”