After Josh Bailey gave the Islanders an early 1-0 lead, the Blues answered with single goals in the first and second periods and two in the third.
After Bailey gave the Islanders a 1-0 lead at the 5:10 mark of the first period, Brewer tied the game with a slap shot at 8:02.
Berglund scored what proved to be the game-winner from between the two circles with 4:37 remaining in the second period.
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