"Disappointing" isn't a word Blackhawks coach Joel Quenneville has used much during his postgame news conferences this season, but it was an apt description after a third-period meltdown resulted in the Hawks' second consecutive heartbreaking defeat.

"We didn't respond to the challenge that was there," Quenneville said after the Hawks fell 5-4 to the Kings on Monday night at the United Center. "It was disappointing how we played and what we gave them."

Holding a 4-3 advantage midway through the third, the Hawks collapsed under pressure from the defending Stanley Cup champions as goaltender Corey Crawford yielded scores to Tyler Toffoli with just under 12 minutes remaining and Dustin Brown with 1:27 left to fall for the second game in a row after holding a lead late. On Wednesday night, the Ducks roared back to steal a 4-2 win from the Hawks, and it was more of the same Monday night in front of a stunned crowd of 21,850.

"We didn't play very well with the lead," said Hawks winger Patrick Kane, who scored his team-leading 17th goal of the season late in the second period. "Tough loss for sure. We haven't really gone through this before where we've kind of struggled a little bit. Two tough losses, hopefully we can get it back" Tuesday night against the Flames.

In addition to Toffoli's and Brown's third-period scores, the Kings received a goal and an assist from Anze Kopitar while Jarret Stoll and Dwight King also found the back of the net.

With Marian Hossa sidelined with an upper-body injury that a source said is the veteran's shoulder, Quenneville inserted Michael Frolik on the top line with fellow winger Brandon Saad and center Jonathan Toews, and the line clicked in the losing effort.