TORONTO -- Overcoming a one-goal deficit to win a game is nothing special in the NHL. Teams do it pretty much every night of the season.
Doing it twice on the same night is not exactly rare, but, when a club does it three times, that is noteworthy.
And when a team is obliged to try to do it four times, as the Penguins were in their 4-3 loss against Toronto at the Air Canada Centre Saturday night, well, that is a bit unrealistic.
"To come back three times is a lot to ask," Penguins winger Craig Adams said. "To come back four times was too much to ask."
Especially for a team that had yet another core player wrenched from its lineup because of an injury.
The Penguins already were missing forwards Sidney Crosby and Tyler Kennedy and defenseman Zbynek Michalek and were forced to play without center Jordan Staal, who sustained an unspecified leg injury in their 3-2 shootout victory against the New York Islanders Thursday.
Staal was hurt in a collision with Islanders center John Tavares early in the second period. He went directly to the bench, then to the locker room, but he returned to the game a few minutes later and finished it.
Coach Dan Bylsma described him as "day to day" and said his status for practice Monday -- no workout is planned today -- has not been determined.
The loss snapped the Penguins' five-game winning streak and dropped their record to 8-3-2.
And it was, in large part, a by-product of their inability to neutralize Toronto's power play.
The Maple Leafs became the first team to score a five-on-four power-play goal against the Penguins this season. And they did it twice.
The Penguins entered the game with a ridiculous penalty-killing success rate of 97.3 percent. And while they had no way of knowing the Maple Leafs would burn them a couple of times, they realized that level of success could not be sustained indefinitely.
"You go through a good stretch and, sure enough, you're going to get a couple in a row [scored on you]," Adams said. "Credit them. They made good plays on both goals, but it certainly caught up with us."
Both of Toronto's power-play goals came while Evgeni Malkin of the Penguins was in the penalty box.
The Penguins' power-play efficiency was not as good as that of the Maple Leafs, who were two-for-two with the extra man and needed a total of 28 seconds to generate those two goals, but they did match Toronto's output, converting two of four tries with the extra man.
The winning goal, however, came at even strength, when Toronto's Phil Kessel beat goalie Brent Johnson from the inner edge of the left circle to break a 3-3 tie at 10:08 of the third period.
Kessel, who leads the NHL with 10 goals, did not get a puck on goal during the first two periods, but shot 50 percent from the field in the third.
"We matched his speed," Penguins defenseman Kris Letang said.
"We didn't give him too much room in the neutral zone to skate with the puck. At the end, the puck found him, and he scored a big goal for them."
Toronto opened the scoring with a power-play goal by Mikhail Grabovski at 11:31 of the first period, as he steered a Dion Phaneuf rebound between Johnson's legs.
The Penguins got that one back at 10:21 of the second, when Matt Cooke swiped a rebound between the legs of Toronto goalie Jonas Gustavsson for his fourth of the season.
Toronto countered quickly, however, ringing up another power-play goal when Tim Connolly tossed in a shot from close range at 11:30.
The Penguins' power play struck back at 15:06, when Chris Kunitz punched a Malkin rebound past Gustavsson for his fourth.
Toronto then took its third lead of the evening at 3:08 of the third, with Clarke MacArthur collecting the puck after a Phaneuf shot caromed off the right goal post and tossing it by Johnson.
The Penguins pulled even for the final time during a two-man advantage at 7:59 on a Malkin goal.
Shortly after Toronto returned to full strength, however, Kessel got the goal that closed out the scoring.
"It's tough to give up goals right after you score and get back in the game," Kunitz said. "Every time we bounced back, they didn't get down. They kept coming forward and getting one more goal ahead of us."
And, finally, after fighting from behind most of the evening, even a one-goal deficit was too much for the Penguins to bounce back from.
"We're doing good things, but we're not able to play 60 minutes the way we should," Kunitz said. "That's maybe why we didn't get a win tonight."
Dave Molinari: Dmolinari@Post-Gazette.com or Twitter @MolinariPG.