WASHINGTON - Rather than give the likely opening- night roster a spin in the final preseason game, the Islanders' brain trust thought Sunday's game against the Capitals needed a dose of youth.

So the back row of the press box at Verizon Center was the place to find John Tavares, Nick Leddy, Johnny Boychuk and Travis Hamonic, among others. A handful of rookies got one more chance to make an impression, and the decisions were made after the 6-2 loss to the Capitals.

The Islanders sent forward Kirill Petrov and defensemen Scott Mayfield, Adam Pelech and Kevin Czuczman to Bridgeport (AHL) and sent talented 18-year-old center Mathew Barzal back to Seattle of the Western League. That left 24 players on the active roster.

That number includes three goaltenders. With Jaroslav Halak (upper body) still sidelined, Thomas Greiss got a chance to get more NHL-level work in. It has become increasingly likely that Greiss, signed July 1 to back up Halak, will be in goal when the Isles open the season Friday at Barclays Center against the Blackhawks.

With four rookie defensemen in front of him, Greiss got plenty of action. The Capitals scored three times in a 2:30 span in the first period, then twice on the power play in the second before rookie Stephon Williams took over in goal.

"Every game in the preseason is important, even if it doesn't look pretty," said Greiss, who made 13 saves. "I feel good about my game right now."

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Greiss has never made more than 25 appearances in a season.

Still, the Islanders have confidence if the goaltending duties on opening weekend -- a home-and-home against the defending Stanley Cup champions -- fall on the 29-year-old's shoulders.

"If things play out where it's Thomas that gets a shot, he'll play hard and give us a chance," coach Jack Capuano said. "A lot can happen between now and Friday."

The hope is that Halak, who played only two periods this preseason and hasn't had a full practice in two weeks, will join his teammates on the ice Tuesday at the Naval Academy rink in Annapolis.

The Islanders are staying in Annapolis until Wednesday for team activities and two practices.