The 28-year-old Italian scooped gold ahead of Finland's Kaisa Makarainen by just 0.6 seconds as both missed the target on just one occasion on the Austrian circuit.
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Aggressive skiing proved key for the Olympic two-time bronze medallist to cross the 7.5km women's sprint finish line in 21:04.9 and deny Makarainen a third title of the campaign.
Hochfilzen
Highlights: Men's rely at Hochfilzen
16/12/2018 AT 14:39
Russia's Ekaterina Yurlova-Percht finished third after shooting cleanly throughout but could only finish 24.4 seconds behind the leader.
The victory ensures Wierer retains the yellow bib as the leader of the season-long overall rankings heading into the 10km pursuit in Hochfilzen on Saturday.
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Sweden claim relay title in Hochfilzen
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Italy claim victory in 4x6km race in Hochfilzen
16/12/2018 AT 12:09