Duclair cut it to 4-1 on the power play at 18:51, beating Thompson glove side from inside the right circle.
Schaefer got the Islanders within 4-2 at 4:28 of the third with a power-play goal. With bodies in front and the puck loose after Thompson made three quick saves at the right post with his right pad, Schaefer dove at the edge of the crease and got enough of the puck to flip it over Thompson's pad.
“I think I’ve seen the exact same scene in ‘The Mighty Ducks’ or something,” Schaefer said. “It was good. Obviously the big thing with me is just, I love to win. I thought we battled back, and I thought it was a great fight back for sure.”
The Capitals used a coach's challenge for a missed game stoppage, contending that there was a hand pass prior to the goal, but the call on the ice was upheld.
Schaefer finished with eight shots on goal, 14 attempts and 26:04 of ice time, all game highs.
“I just thought we were playing on our toes,” Capitals coach Spencer Carbery said. “Guys were being aggressive in really, really good spots. And so it set us up for the night, to have the start we did. And we were able to hang on and face some adversity in the third period. They pushed, and you could feel the energy in the building come alive there, and we had to hang on.
“And sometimes at the beginning of the year, you're trying to work your way through those things. We don't have a win yet. Guys are a little nervous. You're gripping the sticks. So I don't mind the way that finished, of us having to grind through that and hang on and battle a little bit of adversity.”
NOTES: Schaefer (18 years, 36 days) became the second-youngest defenseman in NHL history to score a goal. Ross Johnstone scored at 17 years, 207 days for the Toronto Maple Leafs in 1943-44, then scored again later that season at 17 years, 328 days. … Protas has four points (two goals, two assists) through the first two games of the season.