Hertl, a 19-year-old, first-round draft pick from the Czech Republic, gave the Sharks the quick lead after getting the puck in the neutral zone and beating two defenders up the middle for a backhander past Coyotes goalie Mike Smith.
He doubled the advantage on a tip-in of a Matt Irwin shot less than 7 minutes later and San Jose went on to record a second straight win to start the season.
Oliver Ekman-Larsson got the only goal for the Coyotes, who were coming off a 4-1 win over the New York Rangers in their season opener.
Smith was hung with the loss despite stopping 47-of-50 shots.
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