An already depleted Islanders defense was dealt another blow in the second period of Tuesday’s 2-1 overtime loss to the Capitals, when Lubomir Visnovsky had to leave the game after a crushing hit by Washington’s Tom Wilson.

Visnovsky didn’t return and the Islanders weren’t happy about the hit.

“He’s an idiot,” Kyle Okposo said of Wilson, who was hitting hard throughout the game and wound up being penalized twice nearly in succession in the second period. “That guy runs around, he hits reckless. He jumps, leaves his feet. There’s no place for that.”

Coach Jack Capuano wasn’t pleased, either.

“From the bench, from my view, [Wilson] left his feet,” Capuano said.

Visnovsky’s absence left the Isles with just five defensemen the rest of the way. Eventually, that took its toll.

The Islanders have been without Travis Hamonic, forcing Johnny Boychuk to chase Alex Ovechkin around and Brian Strait to play out of position. Capuano had to get even more creative without Visnovsky, who had to be helped off the ice following the charging call against Wilson.

“Our guys gave everything they got, out there, but you’re not gonna play a 60-plus-minute game like that,” Capuano said. “It’s gets real grueling on our defense.”

Capuano wasn’t pleased with how the rest of the team responded to Visnovsky’s absence.

“When we got down to five defensemen, I don’t think our forwards did a great job managing the puck for them,” Capuano said.

The Islanders could only keep Ovechkin down for so long.

The league’s top goal-scorer scored his second of the series to put the Capitals up, 1-0, at 13:06 of the first period.

The Isles were successful, however, in limiting the Caps, and Ovechkin, on the power play. They didn’t commit a penalty until Anders Lee was called for holding at 6:40 in the third and the Isles killed it off.

It made the Caps just 1-for-7 in the series.

Casey Cizikas highlighted a fourth line that was dangerous throughout the game and has been effective all series.

“We’ve got to play like that every game,” said Cizikas, who scored the Isles’ only goal on Tuesday. “They’re a big team and they’re relentless. There’s a lot of banging and that’s what we thrive on.”

According to some Nassau Coliseum workers, as many as 10 seats were replaced after being swiped following the Isles’ Game 3 overtime victory Sunday as the team prepares to leave for Brooklyn next season.

Retired Yankee Hideki Matsui was at the game wearing a No. 55 jersey.