PITTSBURGH — The Pittsburgh Penguins knew the Detroit Red Wings would block their path to winning the Stanley Cup finals. Maybe just not this much.

Penguins coach Michel Therrien all but begged the on-ice officials again Friday to enforce the obstruction rules, arguing that one of his team’s greatest strengths is being taken away by the Red Wings’ defensive tactics.

“It’s something that we base our team with, speed,” Therrien said. “And if we can … use our speed, we’re going to get effect.”

Detroit takes a 2-1 series lead into a pivotal Game 4 in Pittsburgh tonight. A Red Wings victory forces the Penguins to win three straight games to claim the Cup — two in Detroit, where Pittsburgh was outscored 7-0 in the first two games.

Therrien likes how his youthful Penguins are holding up in the finals, saying, “We’re getting better every game.” What he doesn’t like is how, in his mind, the Red Wings are holding up his team.

Therrien complained about the lack of obstruction enforcement before the Penguins’ 3-2 victory in Game 3 on Wednesday, though it wasn’t apparent if his campaign was successful. The Penguins had just three power-play opportunities, though Sidney Crosby scored one of his two goals following Niklas Kronvall’s hooking penalty early in the second period.

Therrien pleaded again Friday for more open ice, especially with Crosby, Evgeni Malkin and Marian Hossa finding it difficult to get through the neutral zone compared to previous playoff rounds.

“If there’s obstruction, there’s obstruction,” Therrien said. “When I see about 13, 14 (video) clips … that I could tell there should be a penalty regarding the (rule) book, I know how it is. I’m not expecting that they’re going to call 14.

“(But) I’m expecting next game, the obstruction calls, they’re going to call it. … And calls are important. You need those calls.”

Therrien also might be campaigning to even up the penalties. Detroit has had 19 power plays to Pittsburgh’s 11, though neither team is doing much with the man advantage. Detroit has two power-play goals to Pittsburgh’s one.

Red Wings coach Mike Babcock refused to get dragged into one of those “he said, he said” debates that often occur between opposing coaches during Stanley Cup off days. He said he doesn’t pay attention to Therrien’s pleas.

“I don’t listen to him,” Babcock said.

Therrien only hopes the officials do, partly because neither Malkin nor Hossa has scored in the series. Each had nine goals in the opening three rounds.

Therrien first complained about the perceived lack of obstruction calls after his team’s 3-0 loss in Game 2 on Monday, then seemed to back off a bit.

“It’s tough to generate offense with the obstruction that they’re doing,” Therrien said Tuesday. “But you know what? They’re doing it the right way. It’s like there’s a dotted line. Sometimes, they cross it a little bit.”

Therrien apparently felt that line was broached again in Game 3.

Calls or no calls, the Penguins face as important a game Saturday as they did Wednesday, when they knew a loss would have all but ended their chances of raising the Cup. Only this time, they’re coming off a victory rather than two poorly played losses.

Babcock is dismissing momentum as a factor, but Pittsburgh forward Max Talbot questioned whether the Penguins or the Red Wings will be more nervous.

The Penguins are riding a 17-game winning streak on home ice and goalie Marc-Andre Fleury hasn’t lost there in 19 games since Nov. 21, or more than six months.

“I don’t think it’s easy for them right now, knowing we won Game 3 and we still have another game to play in this building,” Talbot said. “I can’t really say they’re nervous but, obviously, they’re a little tighter than they were when it was 2-0. I think we have momentum on our side and we’re going to try to build that for Game 4.”

The Red Wings aren’t certain if top-line forward Tomas Holmstrom will play after injuring a hamstring during a Game 3 collision with defenseman Hal Gill. Babcock expects him to be ready, but said it will be the player’s decision.

Holmstrom often stands above the crease, making it difficult for goalies to find the puck, though Fleury said it won’t be a major advantage if Holmstrom doesn’t play.

“It’s always a little tougher as a goalie when you have someone in front, but every playoff, every series, every team puts that guy in there,” Fleury said. “We always did a good job with him and always came out on top.”