PITTSBURGH — The talk in Pittsburgh the past couple of days was that the Penguins, with a record of 7-1 before Tuesday's game against the Blues, were almost boring to watch.

It's amazing what winning a Stanley Cup does to expectations.

Well, for anyone who thought their start wasn't satisfying enough, the defending champs put on a clinic in Tuesday's 5-1 victory over the Blues, who were overmatched from the outset.

Pittsburgh outshot the Blues 43-20, including a whopping 20-3 in the first period, when the Penguins showed they were just getting started. They led 4-0 in the second period before Paul Kariya put the visitors on the scoreboard.

Blues coach Andy Murray was as little concerned about the details as he's been after a game in his four seasons with the club.

"My biggest concern right now is to find out why we had no legs or no energy tonight," Murray said. "It was evident right from the get-go and that's my thing. When you don't have the energy and the legs, you're reaching with your sticks or you're doing things you shouldn't be doing.

"The shots and the total domination by Pittsburgh was pretty clear. To see such a dropoff (from Saturday's 5-0 win over Anaheim) ... it's difficult to understand."

Meteorologists were calling it an Indian summer in Pittsburgh on Tuesday, but inside the Igloo, it was a constant flurry of shots on Blues netminder Chris Mason. The Penguins had the first nine shots on goal.

"For us not to be ready to play the defending Stanley Cup champions is unacceptable," Mason said. "We come off a good second and third period in Anaheim, a very good team. ... I don't know if we're getting a little ahead of ourselves and getting a little cocky and thinking that it should be easier than it is ...

"We worked so hard the last couple of games and then to come out like we did against these guys ... that's what's going to happen."

Brad Boyes registered the Blues' first shot on Pittsburgh goalie Marc-Andre Fleury with 9 minutes, 22 seconds left in the period. But less than a minute later, the Penguins put their 10th shot in the back of the Blues' net. Tyler Kennedy buried a slap shot for a 1-0 lead.

"I was trying to yell on the bench, let's not make it a goal that wakes us up," Blues forward David Backes said. "Let's turn it around before 1-0 and have to fight off a slow start again."

Once again, first-period penalties hampered the Blues. David Perron (delay of game) and Andy McDonald (high-sticking) were whistled for penalties in the period. They marked the 28th and 29th minor penalties of the season against the Blues, and 16 have come in the first period.

The Blues were able to overcome three penalties in the opening frame against Anaheim because of the best 50 minutes the team has played this season.

But not on Tuesday, not against the Penguins.

With McDonald in the penalty box, Pittsburgh's Evgeni Malkin scored a power-play goal with 7:32 remaining in the first period, forcing the Blues to call an early timeout.

It was a welcome break for Mason.

"Actually, there were a few times where I was pretty tired," Mason said. "They're one of the best teams in the league and they were moving the puck around. It was pretty tiring, but that's the way it goes."

As thrilled as Penguins fans must have been after the first period, the Penguins had to be in dismay that their lead was only 2-0.

Initially, it looked like the Blues might be a different team when the second period started. T.J. Oshie had two shots on goal in the first 25 seconds, only one shy of what the team had in the first 20 minutes.

But the Blues helped out Pittsburgh, taking a "too many men on the ice" penalty 6:14 into the period. Ruslan Fedotenko netted a goal on the ensuing power play for a 3-0 Penguins lead, and 36 seconds later, Matt Cooke bumped it to 4-0.

Kariya scored the Blues' only goal of the game later in the second period. Kariya's fourth goal of the season was a deflection of a shot from Erik Johnson.

Blues backup goalie Ty Conklin replaced Mason in the third period and allowed one goal.