Grubauer preserved that two-goal cushion with a big shoulder stop on New York's Josh Bailey, and then he Caps added to their advantage once again, doing so on their first power play opportunity of the evening.
Towards the end of the man advantage, Orlov passed to Nicklas Backstrom in the right circle. Backstrom went down low on the right side to Kuznetsov, who in turn tried to go cross-crease, but the puck popped up and Backstrom alertly swatted it past Gibson at 10:22, ending the Isles' goaltender's night after he was dented for five goals on just a dozen shots.
Former Caps goalie Jaroslav Halak came on in relief at that point.
Grubauer thwarted a Casey Cizikas breakaway opportunity late in the frame, and the Caps goalie also kept the Isles off the board when New York got a gift power play late in the second period.
The Caps didn't have the puck much in the third period as the desperate Islanders tried in vain to climb back into the contest. By the time the Caps recorded their first shot on net of the third period at the 8:24 mark, New York had already teed up 17 shot tries in the third. Washington skaters got in the way of several of those shots, and the rest weren't very threatening.