Lemieux tied the game with 1:18 left in regulation and Straka won it 11:29 into overtime as the Penguins forced Game Seven in their Eastern Conference semifinal series with a 3-2 victory over the Buffalo Sabres.
"This was something good after losing this way the last game," said Lemieux, whose team suffered a 3-2 overtime loss at Buffalo in Game Five on Saturday. "It's good to have a Game Seven to look forward to."
Held without a goal in the previous four games and knocked to the ice after being hit in the face in each of the first two periods, Lemieux slid a puck past goaltender Dominik Hasek off a goalmouth scramble to tie the game at 2-2.
Alexei Kovalev took a slap shot from the right faceoff circle and the puck ricocheted high in the air off the left skate of Sabres center Curtis Brown before landing in the crease.
Hasek lost sight of the puck and did not react until several players scrambled for it. Lemieux warded off a check from Rhett Warrener at the left goalpost and stuffed the puck under Hasek.
"It was one of those plays where he was right there," said Warrener, who called the night the worst of his life. "We were in good shape. When you look for it, sometimes it just gets lost."
The goal was Lemieux's sixth of this postseason -- his first since he retired in 1997 -- and 76th lifetime in the playoffs. He was held to no goals and four assists in the previous four games.
"It was good to see one going in," said Lemieux, the Penguins' owner, who guided them to Stanley Cup titles in 1991 and 1992. "I felt strong the last two or three games."
Pittsburgh, seeded sixth in the East, kept the momentum after the third intermission and carried the play in overtime, with Straka converting a touch pass from Kovalev in front of the net.
Robert Lang outmuscled rookie defenseman Dimitri Kalinin for the puck behind Buffalo's net and fed Kovalev at the bottom of the right circle. Kovalev one-touched a pass in front to Straka, who did the same over Hasek's right pad.
"I wasn't thinking," said Straka, who has two overtime game-winners among his three goals this postseason. "Just trying to put it on the net."
"We were just looking to get it down low," Kovalev added. "Tonight, it went in at the right times for us."
Hasek finished with 30 saves but fell to 22-1 lifetime in the playoffs when leading after two periods.
Straka added a pair of assists for the Penguins, who avoided winning the first two games of the conference semifinals and losing the next four for the second straight season.
"Thursday was what we were playing for," said Penguins rookie Johan Hedberg, who made 16 saves. "Now, it's down to one game."
The fifth-seeded Sabres were moments away from returning to the conference finals for the third time in four seasons. They host Game Seven on Thursday.
"We worked all year for the home-ice advantage," Sabres left wing Dave Andreychuk said. "That's what we have going for us. This game is done. They win the game in overtime. We now look to Thursday."
The Sabres opened the scoring midway through the first period, when Maxim Afinogenov raced out of the penalty box and beat Hedberg on a breakaway for his second goal of the playoffs.
Kovalev scored his fourth 5:14 into the second to tie it. Hasek committed to the ice, stacking his pads, before Kovalev beat him with a snap shot from below the right hashmark.
"Kovalev scored a big goal to get us going," Lemieux said. "We were getting a lot of chances."
Audette put Buffalo back on top with 4:48 left in the second, when he beat Hedberg from the right circle off a deflection in the slot for his third goal.