ST. LOUIS -- Jaden Schwartz hasn't scored during the St. Louis Blues' current four-game winning streak, but he has been their best player during that span.
Patrik Berglund also scored and Carter Hutton made 21 saves as streaking St. Louis stayed two points behind Nashville for third place in the Central Division.
"It probably sounds simple, but we just try to fight for each other, put each other in a good spot and that's how we win games," Tarasenko said.
Brock Nelson, Anthony Beauvillier and Nick Leddy scored for the Islanders and Thomas Greiss made 20 saves.
Beauvillier cut the Blues' lead to 4-2 at 2:11 of the third period after his slap shot went off Hutton's glove.
Leddy's power play goal with 1:29 left sliced the Islanders' deficit to 4-3.
The Blues entered the game, the second of a back-to-back, without Colton Parayko and Jori Lehtera, who were injured during Friday's game. Then Paul Stastny fell ill, leaving St. Louis three starters short.
"It was going to be a character game," Blues coach Mike Yeo said. "I was confident with the character in our locker room that the guys would recognize that and we would respond."
Schwartz more than made up the difference. Even though he hasn't scored since Feb. 15, Schwartz has been on the ice for the Blues' last eight goals and has had a vital part in most of them.
"He's a machine with the puck, he's hard to get off of it," Hutton said. "He makes so many smart plays. I think he makes everyone around him a better player."
Tarasenko gave the Blues a 1-0 lead with a power play goal at 7:23 of the first period. Schwartz set it up with a nifty no-look, behind-the-back pass to Tarasenko.
"It's almost mind-boggling that he hasn't scored lately, but who cares because he's doing so many things to help us win," Yeo said of Schwartz. "There's so many parts to his game. If you go back and watch the tape, it's all the little things that winners do."
Andrew Ladd appeared to tie the score four minutes later with a power play goal, but the Blues successfully used their coach's challenge and the play was ruled offside.
Steen made it 2-0 off a lucky bounce at 4:58 in the second period. Tarasenko's pass was intended for Schwartz, but it deflected off Islanders center Anders Lee right onto Steen's stick.
Though Schwartz wasn't credited with the assist, his pass helped create the scoring sequence. Schwartz has six assists in his last six games.
"He's easy to play with," Steen said. "He's energetic. He reads the play well, he's easy to read off of and quite frankly it was a treat playing with him tonight."
Nelson scored his second goal in as many games, getting the Islanders on the board with 8:23 left in the second period. Scott Mayfield, a St. Louis native playing his first NHL game in his hometown, got an assist.
Tarasenko got the goal back four minutes later with a wrister from above the right circle. Tarasenko's 32nd goal of the season made it 3-1 Blues and was his fourth goal in the past three games.
"He doesn't need much space to get a shot off and obviously it was apparent tonight he didn't need it at all," Lee said of Tarasenko. "He snapped a couple home. We play against great players like him all the time, but we obviously have got to play him a little tighter."
Berglund extended the Blues' lead to 4-1 late in the second period with a pretty backhand-forehand combination after David Perron found him alone in front of the net.
The Islanders finished a marathon nine-game road trip with a 5-3-1 record. They fell one point behind Toronto for the final wild-card spot in the Eastern Conference.
"We're still in a good spot," Islanders center John Tavares said. "We know we're right there battling for that last wild card. It's obviously tough to finish the season 20-0. There's going to be some games where you don't get the results and you've just to keep moving forward."
NOTES: Blues F Robby Fabbri underwent surgery on Feb. 27 to repair a torn ACL. ... Blues F Ivan Barbashev replaced Jori Lehtera, D Jordan Schmaltz replaced Colton Parayko and F Nail Yakupov replaced Stastny in the lineup. Lehtera was hit in the face by a puck and Parayko left with an undisclosed injury during Friday night's game. ... D Scott Mayfield, a healthy scratch for the Islanders the last two games, replaced D Adam Pelech in the lineup. ... Blues F Zach Sanford was a healthy scratch. ... The Islanders also scratched C Alan Quine, C Shane Prince and D Johnny Boychuk. ... The Islanders host Carolina on Monday. The Blues travel to Los Angeles on Monday.