Patrick Kane tapped home the tying goal as Chicago rallied from a second-period deficit to beat the Kings, who hadn't lost at home since March 23. Bryan Bickell had a goal and an assist for the top-seeded Blackhawks, who took a 3-1 series lead.
"They were playing so well at home, and to finally break that streak, we're happy about it," Hossa said. "We knew about it. We talked about it before the game. We were hoping to break it, and we got it."
Slava Voynov and Dustin Penner scored for the Kings, who had won their first eight playoff games at Staples Center. The champs are in trouble after Jonathan Quick failed to match Corey Crawford, who made 19 saves.
The Blackhawks won without top defenseman Duncan Keith, who served a one-game suspension for high-sticking Jeff Carter in the face during the second period of Game 3. Keith easily is the Hawks' ice-time leader and top-scoring defenseman, but Sheldon Brookbank filled in while Chicago played strong team defense in front of Crawford, who has matched the Conn Smythe Trophy winner in the other net.
"We knew our defense was going to step up, and they did," Bickell said. "We had a good feeling coming in. We had a bitter taste from the last game. They had a big start, but we stuck with it and eventually got it back."
Los Angeles hadn't lost a playoff game at home since Game 4 of the Stanley Cup finals last season, winning nine straight overall, but the Blackhawks figured out how to end the NHL's longest home postseason winning run since 2009. The Kings had been outstanding when playing with a lead in front of Quick, who stopped 25 shots, but Los Angeles uncharacteristically surrendered a 2-1 lead late in the second period.
The high-scoring Kane ending his seven-game goal drought in a quiet postseason by charging into the crease to tap home the tying goal on a rebound of Niklas Hjalmarsson's shot and Bickell's deflection late in the second period. Hjalmarsson finished with two assists.
After Los Angeles killed a penalty to open the third period, Michal Handzus caught the Kings napping and set up a break with the speedy Hossa, who ripped a precise shot for his seventh goal of the postseason.
Pittsburgh at Boston, 6 p.m., NBCSN
Bruins lead series 3-0
• Los Angeles at Chicago, 6 p.m., NBCSN
Blackhawks lead series 3-1