Playing on consecutive nights for the first time this postseason, the Lightning extended their winning streak to seven games and advanced to the Eastern Conference finals for the first time since their 2004 Stanley Cup championship season.

For Alex Ovechkin and the Capitals it was yet another bitter postseason disappointment.

Rookie Michal Neuvirth stopped 32 shots for Washington, but Bergenheim scored twice in eight minutes during the second period to build a 3-1 lead that induced chants of “sweep, sweep, sweep’’ from a sellout crowd of 20,835.

The Lightning’s big three of Martin St. Louis, Vincent Lecavalier, and Steven Stamkos have elevated their games, but so has Bergenheim, who has a team-leading seven goals through two rounds. St. Louis’s sixth goal of the playoffs, with 3:08 remaining, finished Tampa Bay’s scoring.

Ryan Malone and Marc-Andre Bergeron added goals for the Lightning, who have not lost since dropping into a 3-1 hole against the Pittsburgh Penguins in the first round.

Marco Sturm, John Erskine, and John Carlson scored for the Capitals.

The Lightning were expecting the toughest game of the series last night, calling the Capitals a proud team that would not be taken lightly. Washington felt the first three games could have gone either way, with Ovechkin insisting after Game 3 that the series was far from over and that he expected his team to come back and win.

Malone scored with Ovechkin in the penalty box for charging, giving Tampa Bay a 1-0 lead at 12:37 of the first period. The Lightning have not lost a game in the playoffs in which they’ve scored first, however Washington proved again to be resilient after falling behind early.

The Capitals tied it late in the first, scoring for only the second time in 17 power-play opportunities in the series. Jason Arnott and Ovechkin assisted on Sturm’s goal, however Washington couldn’t build on the momentum during a second period in which it was outshot 17-10.

Bergenheim’s sixth and seventh goals of the playoffs put the Lightning up, 3-1.

Sharks 4, Red Wings 3 — Devin Setoguchi scored 9:21 into overtime to finish a hat trick, and San Jose took a commanding 3-0 series lead in the Western Conference semifinals with a win in Detroit.

The Sharks will have a chance to sweep the series tomorrow night in Detroit.

San Jose’s Dan Boyle scored the tying goal with 4:08 left in regulation, setting up the Sharks’ second overtime win of the series.

Pavel Datsyuk scored a go-ahead goal late in the second period, but Detroit couldn’t hold on.

The Red Wings also didn’t capitalize when Setoguchi went to the penalty box at 5:14 of overtime for holding, failing to score a third power-play goal.

San Jose made them pay for it with Joe Thornton getting the puck to Setoguchi at the top of the right circle for a wrist shot that went across goalie Jimmy Howard and into the net.

Antti Niemi stopped 38 shots for the Sharks. Howard made 34 saves.

Setoguchi scored first, a power-play goal midway through the first period, and made it 2-all late in the second with another man-advantage goal.