The Islanders will sink or swim with Evgeni Nabokov. Despite being pulled for the second time in the series during the third period of Game 5’s ugly 4-0 loss to the Penguins in favor of youngster Kevin Poulin, the veteran will be back between the pipes for tonight’s make-or-break Game 6 at Nassau Coliseem, coach Jack Capuano said. A key to the Islanders reaching the playoffs, Nabokov, 37, has struggled in the series, allowing 20 goals in the five games, to go with an unsightly 4.68 goals-against-average and .847 save percentage. He never has been a particularly strong playoff performer, with a lifetime 42-41 record. “Every goalie, if you ask them, would like to have one or two back,” Capuano said. “I have confidence in [Nabokov] to continue to go with him. He’ll start again [tonight], it’s no surprise. We’ll move along with him. He’s a veteran guy, he’s probably harder on himself than anybody else. He knows how he has to play.” Nabokov said the Islanders need to improve upon “a combination of everything” to force a Game 7. He did fault himself partly for the lopsided loss Thursday night. “It doesn’t matter how the game goes, it’s always important if you have a big stop,” Nabokov said. “It starts with big saves at the right time.” * Already down one of their top defensemen, the Islanders could be without second-line center Frans Nielsen tonight. The hard-working pivot suffered what the team has termed a lower-body injury in the third period of Game 5, and wasn’t on the ice during the team’s optional skate yesterday.