"We were quick to find out why they're the Stanley Cup champions," said Leafs forward Tim Brent. "They capitalized on every mistake we made. We just kind of got away from what we've been doing so well lately ... and it came back to haunt us."
With Toronto chasing its first playoff berth since 2004, the fans were amped up at Air Canada Centre -- at least for the opening minute. Shortly after, Leafs defenseman Carl Gunnarsson turned the puck over to Hossa, who beat James Reimer for his 18th of the season at 1:10.
"We had a horrific giveaway right at the wrong time," Toronto coach Ron Wilson said. "That energized them and deflated us a bit. They took advantage like good teams do."
The Blackhawks didn't let up, extending their lead to 3-0 when Frolik finished off a 2-on-1 at 4:13 and Toews converted a pass from Patrick Kane with 3:23 left. The Chicago captain has eight goals and 15 points during his nine-game run.
Lupul briefly restored some hope for the home fans by intercepting a pass at his own blue line and beating Corey Crawford high at 7:28 of the second period, but Stalberg and Bickell scored before the intermission to bring an early end to Reimer's night.
"We have an expectation to win and get the two points and I think it's showing in the way we're starting games," Blackhawks defenseman Duncan Keith said.
Reimer was replaced by Jean-Sebastien Giguere to start the third period after allowing five goals on 19 shots. Reimer was tagged with his first regulation loss since Feb. 5.
The Leafs pushed hard to get back in the game in the final 20 minutes.
After Crabb scored at 4:26 on a play where the puck took a couple strange bounces, Mikhail Grabovski was hauled down on a breakaway. He made a nice deke that was denied by Crawford, who followed that up with a nice breakaway save on Mike Brown.
"(Crawford) was great in the third period, made a great save on the penalty shot," Blackhawks coach Joel Quenneville said.
Schenn scored in the final minute.
"It's good experience for our team to play one of the better teams in the League right now and see what we have to do to get better," Wilson said.
Material from wire services and team media was used in this report.