Nothing comes easy for the Flyers these days.

Not even when the opponent is the worst-in-the-NHL Buffalo Sabres.

Not even when they build a two-goal lead for the first time in 13 games.

They huffed and puffed Sunday afternoon against the woeful Sabres and then, stunningly, collapsed in the last few minutes, turning a 3-2 win into a 5-3 loss to Buffalo at the Wells Fargo Center.

Jeff Skinner and Rasmus Asplund scored 25 seconds apart late in the game to give Buffalo a shocking comeback win, crippling the Flyers’ already-slim playoff hopes.

Shayne Gostisbehere’s goal early in the third period gave the Flyers a 3-2 lead, but Skinner scored on a rebound – it went off his foot, but it was ruled it was not with a distinctive kicking motion – with 3 minutes, 3 seconds left. Carter Hart then couldn’t control a rebound and Asplund scored with 2:38 remaining to make it 4-3.

Buffalo added an empty-net goal.

“It’s hard to explain,” coach Alain Vigneault said in a glum tone. “We had that game in total control and we were giving them almost nothing. We just blew it.”

An icing by Claude Giroux occurred 11 seconds before Skinner’s game-tying goal. A giveaway by Sean Couturier (five shots, assist) helped set up Asplund’s winning goal, which is why the Flyers’ MVP snapped his stick over the net.

“Two mental mistakes,” Giroux said. “It’s very frustrating, especially the position we are in right now in the standings.”

“That icing that we didn’t need to do, and a lost puck in our end in the corner when we had control,” Vigneault said. “... Two breakdowns and they win the game.”

The Flyers were coming off a critical 3-2 win Saturday over Boston, the team they are chasing for a playoff spot.

But for what seems like the umpteenth time this season, they failed to build momentum from a key victory.

“Last year we did a good job of being consistent; this year, it’s been a problem,” Giroux said. “... Before they scored those two [late] goals, I thought we were playing a good game.”

With the loss, the Flyers remained four points behind Boston for the final East Division playoff spot. The Bruins, who were trounced Sunday night by visiting Washington, 8-1, have two games in hand on the Flyers.

Gostisbehere has three goals in his last four games, and, yes, the Flyers are fortunate he cleared waivers recently. He now has eight goals in 31 games.

“It definitely hurts right now,” Gostisbehere said of a loss that might convince general manager Chuck Fletcher to be a seller before Monday’s 3 p.m. trade deadline. “We’ve got to move on and get some points in these next games.”

On the play that gave the Flyers the 3-2 third-period lead, James van Riemsdyk forced a Buffalo turnover in the neutral zone, and Phil Myers fed Joel Farabee on the right side. Farabee sent a cross-ice pass to Gostisbehere, who put a left-circle shot through the legs of goalie Linus Ullmark with 16:13 left in regulation.

Hart, who has had a mystifying season, has lost seven straight. He made 26 saves, Ullmark made 40.

» READ MORE: Flyers, on the fringe of the playoffs, should look to the future at trade deadline | Sam Carchidi

The Flyers, playing their fifth game in seven days, got first-period goals from Oskar Lindblom and Farabee (team-high 15th) to take a 2-0 lead. It gave the Flyers their first multi-goal advantage since March 18, when they outlasted the Islanders, 4-3. That was also Hart’s last win.

Sunday’s lead didn’t last long. Sam Reinhart and Arttu Ruotsalainen (first goal in two NHL games) scored 46 seconds apart to tie the game at 2 early in the second period.

On a set play that caught the Flyers flat-footed, an uncovered Reinhart, who has scored six of his 14 goals this season against the Flyers, tapped the puck past Hart after Skinner won a draw from Couturier and fed him in front.

Shortly after Ruotsalainen’s goal, Nic Aube-Kubel fired over an open net, squandering a golden opportunity to put the Flyers ahead again.

With 3:35 left in the second, Couturier took a carom off the end boards and, from near the left post, was robbed by Ullmark as he somehow prevented the puck from crossing the goal line.

Buffalo, which ended an 18-game losing streak with a 6-1 win over the Flyers on March 31, was without two of its top offensive players: Taylor Hall, who was being rested because he could be dealt before Monday’s 3 p.m. trade deadline and the Sabres didn’t want to risk an injury, and injured center Jack Eichel.

The Flyers, who finished with a 5-3 record against Buffalo this year, will play in Washington on Tuesday, and Fletcher may make some additions or subtractions before that game.