DENVER — The lesson, hard as it was to learn, was pretty clear after the Islanders dropped a 2-1 decision to the Avalanche Thursday night: Throw the puck on net and you never know what can happen.

Colorado’s Francois Beauchemin did that from along the goal line in the closing minutes of a tie game. His heave banked off Mikhail Grabovski’s skate and past Thomas Greiss for the game-winner at 16:48 of the third period, sending the Islanders to a second straight frustrating regulation loss after an 8-0-2 run.

“Sure it’s frustrating,” said Brock Nelson, who turned the puck over inside the Colorado blue line to start the rush that ended with Beauchemin’s accidental goal. “We did some good things, just not enough.”

The Isles, as they did for much of Tuesday night’s 5-1 loss to the Panthers, had the better of the play against the Avalanche for much of the game. They had a power play gifted them with 8:51 to go when the Avalanche was called for an obvious too-many- men minor but put no shots on Semyon Varlamov during the man advantage.

Josh Bailey sped in off the left wing and tried to thread a pass through to the middle rather than shoot with room to accelerate. The Isles had 34 shots on Varlamov, who was superb, but the late power-play failure gnawed at Jack Capuano.

“We got one [Nelson’s second-period marker] on the power play tonight, but you have that power play with eight minutes left and you don’t get a shot,” he said. “We passed up a shot and decided to make the sexy pass instead. It’s really hurt us lately. We’re not building any momentum off the power play.”

advertisement | advertise on newsday

The third period was surprisingly active for a 1-1 game, with both teams generating chances. The Isles’ opportunities came off a strong forecheck that forced turnovers; the Avs countered with speed. Greiss (28 saves) and Varlamov both were excellent and the game seemed headed for overtime, where at least the Islanders could take a point or two and some consolation.

They were the better team for much of the opening 40 minutes, save a six-minute stretch in the first when they were stuck in neutral. After John Tavares and Thomas Hickey crossed signals on a breakout pass, Beauchemin’s screened wrister beat Greiss at 3:48 to open the scoring.

The Avs had a couple of three-on-ones off Isles breakdowns, but the visitors gathered themselves and started to force the play. The only thing that was missing was a goal until Nelson snapped one past Varlamov at 4:55 of the second through Anders Lee’s screen.

There wasn’t enough traffic in front of Varlamov as the game wore on, however. “We just didn’t find a way to get those Grade-A [chances],” Nelson said.

The Islanders headed to Arizona with only two goals in their last two games despite playing well enough to come away with points.

“We had some games earlier this year we had no business winning and we got the two points,” Capuano said. “We come here, play a pretty solid game and get beat by a puck off a skate. It happens sometimes.”

Notes & quotes: A source said 2008 draft pick Kirill Petrov, who was a late cut out of training camp, is considering going back to Russia. The forward has spent the entire season in Bridgeport and has a goal and four assists in 12 games. He recently returned from missing six weeks because of a broken foot.