The American forward volleyed home the winner for AZ as it handed the league leader its first loss of the season.
The U.S. national team striker scored a stunning winner in the 57th minute of AZ's 2-1 triumph Saturday over league-leading PSV, which suffered its first loss of the campaign. At 4-3-1, AZ is now tied for second in the Eredivisie.
The goal was Johannsson's fifth in six league matches played. The 22-year-old also scored in Europa League play last month and bagged a hat trick earlier this week in the Dutch Cup.
Settling a loose ball 25 yards from goal, Johannsson chested it down and struck a dipping volley on the bounce that beat goalkeeper Przemyslaw Tyton.
AZ returns to action Thursday with a Europa League tilt against Greek side PAOK.