Kovalchuk dished to Alexei Ponikarovsky, who snuck the golden goal through Ilya Bryzgalov's five hole with 2 minutes, 39 seconds remaining in overtime, handing New Jersey a series-pivoting, 4-3 victory Thursday night in front of 17,625 frothing fans at the Prudential Center.
"I don't know if I panicked or what," Gustafsson said. "I saw Kovalchuk come on and I wanted to come off so we could get the right matchup. I thought I had time to get off so [Braydon] Coburn could get on the ice. Obviously, that wasn't the case. It was a stupid mistake."
It was the Flyers' first overtime loss in three games this postseason.
But it wasn't all Gustafsson's fault. The Flyers squandered two power plays in the lengthy overtime session, along with Danny Briere's nightly magic, after he sent the game past regulation when he evened the score at 3-3 with 8:56 to play in the third period.
"We didn't score the goals," Jake Voracek said. "We've got to make sure that we do a better job, especially in overtime when we get that second power play. We've got to make sure we bear down and bury them."
Now, the Flyers face the daunting and damning task of their first playoff series deficit of the postseason, as New Jersey holds a 2-1 lead in their best-of-seven Eastern Conference semifinal series.
"It was a tough break," coach Peter Laviolette said of the ill-fated change. "It seemed like we had a line change going and they caught us on it. [That pairing] played a regular shift. We were coming off of those power plays. 'Gus' and Lilja are part of that rotation. They've done a nice job for us."
In the last four playoff series between the Flyers and Devils, the team leading 2-1 has gone on to win the series three times.
The Flyers are 13-19 all-time when dropping Game 3 of a series, regardless if they were leading or trailing at that point. Overall, they are 7-19 in a series when trailing by two games to one. In that case, the Flyers have battled back to knot the series in Game 4 exactly half the time (13-for-26).
With an extra day off in the series to rest and recuperate - particularly for forward Sean Couturier, who limped off the ice in the first period and did not return with a "lower-body" injury - both teams will have an opportunity to re-evaluate. Game 4 is Sunday night in Newark.
Game 3 was a matchup of seesawing momentum. Back and forth it went.
After Brayden Schenn gave the Flyers a 1-0 edge on the power play 6:08 into the game, they managed just two shots for the rest of the period.
The Flyers are 1-4 when scoring the game's first goal in the playoffs. Inexplicably, they are 4-0 when the opponent scores first.
New Jersey owned the puck after Schenn's tally, scoring twice in a span of 20 seconds - once on the power play and once off a defensive breakdown - to take a 2-1 lead to the locker room at the first intermission. Patrik Elias and Kovalchuk combined to set a New Jersey franchise record for fastest goals scored in a playoff game, breaking a record held from a May 14, 2000 game against the Flyers.
The Flyers' first period was so putrid that four of their six defensemen finished without a hit against a Devils team that spent most of the first 20 minutes circling and cycling around their net. At times, the Flyers seemed stunned by the relentless pressure of New Jersey's forecheck - even though they saw plenty of video on it after their Game 2 loss.
Back and forth. Predictably, momentum flipped in the second period, where the Devils have been outscored, 12-4, in these Stanley Cup playoffs. Matt Carle pinged the far side of the net on a slap shot 5 minutes into the second period.
The Flyers outshot New Jersey, 9-2, in the second and even had a goal disallowed because of goaltender interference.
Back and forth. After Zach Parise gave the Devils a 3-2 lead in the third, the Flyers were finally able to swing the puck-possession pendulum in their favor when Briere came to the rescue.
"We've got to take the positives out of this game," Gustafsson said. "We battled and we came back. I'm pretty sure you will see a whole different team next game."
Now, the Flyers - kings of the comeback - will have their mettle tested in a brand-new way.
"Everyone thought we were going to sweep, we were such big favorites," Voracek said, adding that it didn't feel strange to trail for once. "We knew it wasn't going to be easy."
Contact Frank Seravalli at email@example.com or @DNFlyers on Twitter. Read his blog, Frequent Flyers, at www.philly.com/frequentflyers.