The Islanders built their team around goaltending, but they are now just one play away from a disaster in nets. 

Semyon Varlamov did not dress for Friday’s game against the Capitals and was declared day-to-day with an undisclosed injury.

Coach Lane Lambert said it was undecided whether Varlamov would travel on the team’s four-game road trip that starts in Pittsburgh on Sunday and rolls through the Southwest. 

Ken Appleby was called up from AHL Bridgeport to back up Ilya Sorokin.

But realistically, Sorokin will be expected to start every game until Varlamov is back healthy. 

“Very confident [in Appleby]. He’s played well down there,” Lambert said of the 28-year-old, who has an .898 save percentage in 10 AHL games this season. “And so we’ll see. We’ll see what happens.” 

The Islanders have leaned on Sorokin for extended runs while Varlamov has been injured twice before. Sorokin started nine straight games to begin the 2021-22 season including a back-to-back, compiling a .939 save percentage as the Isles started the campaign 5-2-2.

Then last season, Sorokin started 12 of 13 games between Dec. 19 and Jan. 16, again including a back-to-back and again with an impressive .934 save percentage. 

So, even coming off a disastrous six-goal outing against the Penguins on Wednesday that dropped his save percentage to a career-worst .909, the concern is less with Sorokin’s ability to handle the workload and more with what might happen if he were to suffer an injury. 

Of course, that is a possibility over which the Islanders have little to no control. But they can give Sorokin a lighter workload by allowing fewer shots than the 36 per game he has faced thus far. 

“Every night but especially [now], we got to try and make things easier for our goaltenders,” Noah Dobson told The Post. “Make sure they’re seeing the puck, we’re tying up sticks, boxing out and then just managing the game where we’re not giving up those grade-As, breakaways, two-on-ones, stuff like that.

“But he gives us a chance every night to win. We gotta do our part in front of him, put a good effort in.” 

Scott Mayfield (upper body) continued to skate with the group but did not return to the lineup against the Capitals. Lambert said he was optimistic that Mayfield would be able to travel with the team. 

As for Adam Pelech (upper body) and Ryan Pulock (lower body), the head coach was unsure whether they would be on the road.