TAMPA, Fla. -- Just making the postseason is not enough for the Tampa Bay Lightning.
"It's not our goal to get in and be happy with the first round," said left wing Ryan Malone.
Steve Downie also scored for the Lightning, who have won three in a row following a four-game losing skid.
"A very good team," Penguins coach Dan Bylsma said. "A scary team."
Dwayne Roloson made 36 saves, including 16 of 17 shots he faced in the third.
"They deserve it," new Tampa Bay owner Jeff Vinik said. "We're excited to be in the playoffs. It's great to see the results on the ice."
Pittsburgh, which had won its previous four road games, got a goal from Mike Rupp. The Penguins missed out on a chance to move within two points of Atlantic Division-leading Philadelphia, which lost 1-0 to Atlanta.
"We've got to finish strong," Rupp said. "Our goal is to have Game 1 [of the playoffs] in Pittsburgh."
Penguins center Sidney Crosby, sidelined for nearly three months with a concussion, resumed skating with his teammates in practice. The Pittsburgh captain, out since Jan. 6., is not ready yet to participate in full practices. A return to game action for the postseason has not been completely ruled out.
Downie put the Lightning up 1-0 with a backhand rebound goal at 4:51 of the first.
St. Louis made it 2-0 with 9:47 left in the opening period. Vincent Lecavalier set up the goal with a check on Penguins defenseman Kris Letang that resulted in St. Louis picking up a loose puck and then beating Marc-Andre Fleury from just below the right circle.
"The credit goes to the players," first-year Lightning coach Guy Boucher said. "It's a bunch of new people trying to accomplish something. Everybody trying to do their part. We wanted to change the culture."
Lecavalier has six assists and eight points during a six-game point streak. The Lightning captain has 12 assists and 24 points in his last 23 games.
"It's the beginning," Lecavalier said. "It means a lot. We had a few tough years."
Rupp cut the deficit to 2-1 on the Penguins' seventh shot of the period on Roloson 4:31 into the third. The center stopped a personal 13-game goal drought.
"I think it showed in the second and the third the way we can control a game and really press on a team," Penguins center Jordan Staal said. "If we start off like that and do that for three periods, it's tough for a team to face that."
Pittsburgh, including five failed chances Thursday, has just two power-play goals in its last 50 opportunities.
Malone returned after missing 21 games due to a mid-body injury. ... The Penguins are 19-13-5 this season with Crosby out of the lineup. ... St. Louis has scored a goal in three consecutive games. The right wing has scored 30 or more goals in a season five times. ... Fleury had 22 saves.