WASHINGTON — Mike Green’s two power-play goals less than 1½ minutes apart in the third period and Alex Ovechkin’s NHL-leading 54th tally helped the Capitals beat the Islanders 5-3 last night.

Green’s 18 man-advantage goals set a franchise record for a defenseman, breaking the mark of 16 held by Scott Stevens. Ovechkin has 33 home goals, one more than the Capitals record he set in 2007-08.

Kyle Okposo and Frans Nielsen each had a goal and an assist as the Isles took a 2-0 lead. Okposo put them in front with his team-high 18th goal about 14 minutes into the game — and 12 seconds into a power play — off a pass from Nielsen.

The Isles scored again only 37 seconds into the second period when Okposo and Jeff Tambellini set up Nielsen’s goal. The puck appeared to go in off Nielsen’s skate, but the goal was allowed after a video review.

Richard Park also scored for the Isles 2:12 into the third, flipping a backhand past Jose Theodore.

After goals by Ovechkin and Keith Aucoin, the Caps tied it at 3-3 when Green took a cross-ice pass from Alexander Semin and sent a one-timer past Joey MacDonald 10:55 into the third period. Then, at 12:18, Green was barely inside the blue line when he flicked the puck past MacDonald.

“That’s why he’s probably going to win the Norris Trophy this year,” MacDonald said about Green. “It’s not the big, one-timer shot. It’s a nice floater right through, and it’s tough for a goaltender.”

Caps 5 Isles 3