Oshie tipped in Carlo Colaiacovo's shot from the point with 4:11 left in the first period -- only 20 seconds after Torry Mitchell had tied it 1-1 with a tally for the Sharks.
Oshie and Kevin Shattenkirk each had a goal and an assist, and Jaroslav Halak made 18 saves as St. Louis competed a 4-0 season sweep of San Jose and won for the fifth time in six games overall.
The Blues used the triumph to pull into a first-place tie with idle Detroit atop the Central Division.
Antti Niemi turned aside 29-of-32 shots for the Sharks.
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