Thomas Vanek appeared to score the winner for the Islanders on the power play with 1:15 left in overtime but the play was overturned on review. The puck dribbled past Blues goaltender Jaroslav Halak and went to Toronto for review. The puck appeared to hit Vanek's skate but the distinct kicking motion that usually negates goals wasn't apparent.
The Islanders lost for just the fifth time in 15 games.
Kevin Poulin made a number of acrobatic saves for New York. His best was a point-blank pad save on Blues leading scorer Alexander Steen midway through the second. He also denied Steen and Oshie during a power play midway through the third.
Vanek opened the scoring at 4:01 of the first, slapping the puck by Jarolsav Halak for his 19th of the season. Vanek has points in 17 of his last 19 games with nine goals and 16 assists during the stretch.
The 30-year-old left wing was acquired from Buffalo on Oct. 27 for Matt Moulson and two high draft picks. The line of Vanek with centre John Tavares and with Okposo on the right has ignited the Islanders over the past month.
Okposo has points in five straight games and in 18 of his last 22 contests while Tavares (23 goals and 41 assists) is second in league scoring behind Pittsburgh's Sidney Crosby.
The line connected again at 15:11 when Okposo jammed the puck past Halak for his 22nd goal of the year. Fans at Nassau Coliseum also chanted "U-S-A, U-S-A" for Okposo, who wasn't picked for the U.S. team for the Winter Games next month in Sochi, Russia even though he's having a breakout season. Okposo already has a career-high 54 points.
Tarasenko cut the margin in half at 17:17 of the first, beating Poulin high from about 30 feet out. The 22-year-old right wing scored again at 1:17 of the second, his 17th goal this season. He hit the left post late in second and had a golden chance midway through the third when his rebound shot appeared to hit both posts without going into the net.
The Blues won the previous meeting this season, 5-1 at the Scottrade Center on Dec. 5.
The Blues were completing visits to all three local teams. They defeated the Rangers 2-1 on Thursday after losing 7-1 in Newark to the Devils.
St. Louis is 16-3-1 against the East this season. They are 40-10-6 against the East since 2010-11, league-best intra-conference play.
NOTES: The Islanders are 19-6-3 when they score at least three goals and are 2-19-5 when they do not . Ten members of the Blues will represent their countries at the Olympics, tying Chicago and Detroit for the most among NHL teams . The Islanders have led by two or more goals 15 times in their 54 games. They are 6-4-5 in those game