Jonathan Toews made the Vancouver Canucks pay for their mistakes.

The long, lean Toews scored three power-play goals and added two assists in a 7-4 Chicago Blackhawk victory that pushed the Vancouver Canucks to the brink of NHL playoff elimination.

"It was one of those nights where you get some chances," said Toews. "You throw it on net and it goes in.

"It's nice for your confidence and it's nice to get those breaks. You don't always expect to get lucky like that."

Patrick Sharp also had a power-play goal and three assists as the Blackhawks return home with a commanding 3-1 lead in Western Conference semifinal series.

Brent Seabrook scored once while Patrick Kane had two assists for the Blackhawks. Chicago took advantage of the Canucks losing their composure to score four times on eight power plays.

Tomas Kopecky scored in the third period just seven seconds after a Vancouver penalty expired. Dave Bolland also scored into an empty net.

Toews' five points moved him into the playoff scoring lead with 18 points (five goals, 13 assists), one more than Detroit's Johan Franzen.

Kane shrugged when asked if the Canuck had unravelled during the game.

"On our side, we took advantage of some opportunities," he said. "The power play had a heck of a night.

"Overall we played well in the third period and limited their chances."

Daniel Sedin and Alex Edler, on the power play, Kyle Wellwood and Henrik Sedin replied for Vancouver. It was Daniel Sedin's first goal of the series.

Vancouver goaltender Roberto Luongo had no explanation for why the Canucks lost their cool.

"We lost our composure again," said the frustrated captain. "I don't know why it happened.

"We were all on the same page before the game started. One thing led to another and we lost our composure again."

At times Luongo looked rattled and seemed distracted by big Hawks forward Dustin Byfuglien.

That didn't go unnoticed by Vancouver coach Alain Vigneault.

"I think Roberto is the second best goalie in the series," said Vigneault. "But that will change."

Game 5 of the best-of-seven series will be played Sunday in Chicago. If necessary, Game 6 will be at GM Place Tuesday.

Toews' first goal was a rocket of a shot past a screened Luongo in the first period.

He struck against just 27 seconds into the second. Vancouver's Ryan Kesler tried to move the puck behind his own net. Instead he sent it in front of the net where Toews tipped it past Luongo. Before the period ended Toews scored on a scramble during a Chicago 5-on-3.

The two-man advantage happened after Daniel Sedin was sent off for cross-checking, then Alex Burrows followed for roughing. Both penalties showed the Canucks frustration.

Byfuglien, the hulking Hawk who Canuck fans love to hate, earned one assist but played a big role on two other Chicago goals.

He drew a penalty on Vancouver defenceman Sean O'Brien that resulted in Toews' first goal. On the power play, Byfuglien parked his 257 pounds in front of the net and screened Luongo.

In the second period an angry Burrows cross-checked Byfuglien while he was laying on the ice, resulting in the five-on-three.

The penalties Vancouver took that weren't a result of frustration were a result of the Blackhawks speed. Their big, strong forwards flew by the Canucks.

The sellout crowd of 18,810 didn't like the calls. They voiced their frustration by chanting obscenities. Many started leaving midway through the third period.

It was a wild first period played at break-neck speed. Seabrook scored just 18 seconds into the game on an easy looking shot that squeezed through Luongo's pads.

Wellwood tied the match at 1:34 when a Mikael Samuelsson shot deflected off him and past Chicago goaltender Antti Niemi.

Daniel Sedin tied the game at 14:36. Burrows, moved back onto the first-team power play, fired a shot that Niemi stopped, but Sedin was there to score on a rebound.

Notes: Pavol Demitra, who has two goals in the playoffs, and hardnosed Rick Rypien were among the Canuck scratches. ... In an interview with ESPN, Chicago's Adam Burish called Burrows, Kesler, O'Brien and Kevin Bieksa clowns. ... Vancouver is 3-7 in Game 4's since 2001.