Tampa Bay Lightning's Steven Stamkos, center, celebrates with teammate Martin St. Louis as referee Kelly Sutherland signals Stamkos goal with 1:03 left in the game. (Mike Carlson/Associated Press)

The Washington Capitals appeared poised to squeeze at least a point out of Monday’s contest, tied late in the third period against the Tampa Bay Lightning when they did something they couldn’t afford to do — give space to Steven Stamkos.

After losing a faceoff in the defensive zone, the Capitals failed to tie up the stick of the NHL’s leading goal-scorer at the top of the crease, allowing Stamkos to smack a rebound into an open net for an easy goal with 63 seconds remaining in regulation. It would prove decisive in Tampa Bay’s 4-2 victory at Tampa Bay Times Forum.

Washington (40-32-8, 88 points) remains in control of its playoff chances despite the loss, now with only two games remaining in the regular season, but its chances of winning the Southeast Division took a considerable hit. Florida, whom the Capitals host on Thursday, can clinch the division and the third seed in the East with just two points over its final three games.

The Capitals hold the tiebreaker for the eighth and final Eastern Conference playoff spot over the Buffalo Sabres, who sit in ninth with 86 points and three games remaining. But after the game, Capitals players suggested they shouldn’t have allowed this much to be determined in the final week.

“It’s frustrating. We could have really put ourselves in a good spot and put a little bit of a stranglehold on it,” Karl Alzner said. “But now we just kind of took one more step back and made it a lot tougher on ourselves. It gives Buffalo a lot more hope now and we’ve got to remember that we’re battling.

“We obviously let off the gas, and there was a lot of bad turnovers and sloppy play,” Alzner continued. “That’s the sign of a team, that, in my opinion, thinks they had it a little bit too good. It was a big-time error by us. We never should’ve had that game be where it was.”

Tampa Bay (37-35-7, 81 points) had already been eliminated from postseason contention, but made it clear from the beginning it didn’t intend to back down. A message on the video board during the pregame festivities read: “Who said it’s over? There’s always something to play for. For pride. For each other.”

After a scoreless first period and sloppy first half of the second, the Capitals found some life and Alexander Semin rifled a shot past veteran goaltender Dwayne Roloson (31 saves) for a 1-0 lead with 12 minutes 47 seconds gone in the second.

Washington bombarded the Lightning but couldn’t add a second goal as Roloson, who has struggled all season and entered the game with a 3.76 goals-against average and .884 save percentage, grew in confidence with each save. Perhaps Roloson’s best save came when he flashed his glove to rob Mike Green — still searching for his first goal since Oct. 22 — who was speeding down the right wing boards.

“You’ve got to give credit to the goalie there, he had a strong game,” Coach Dale Hunter said. “He had a real good game and unfortunately it came against us right here.”

Tampa Bay withstood that push and went on score a pair of goals 25 seconds apart in the final three minutes of the second — a power-play tally by Teddy Purcell and a blast from the point through traffic by Victory Hedman — to take a 2-1 lead into the third.

Michal Neuvirth finished with 23 saves in his first game against the Lightning since they eliminated Washington in the 2011 playoffs.

Jason Chimera scored his 20th goal of the season on a rebound with 3:17 remaining to even the score at 2. But unlike its previous two contests, both shootout wins, Washington couldn’t manage to force things into extra time to glean at least one point out of an imperfect outing.

Stamkos’s 57th goal of the year, when Dennis Wideman failed to mark him out in front, offered a demoralizing blow. He then added No. 58 with a shot into the empty net to send the Capitals home pondering their flaws once more.

“Not being able to get a single point tied with three minutes left, it’s disappointing to say the least,” Washington winger Troy Brouwer said. “We need to make sure that we’re closing out teams or finding ways to make sure that we’re getting points.”