The prolific striker continued his hot start to the season with his eighth goal in all competitions.
AZ was ahead 3-0 when it was awarded a penalty kick in the 76th minute, which the American striker stepped up and buried to the goalkeeper's right. Viktor Elm had already scored a hat trick for the Eredivisie side, which now advances to the third round of the Dutch cup competition.
The goal was Altidore's eighth in all competitions this season. The 22-year-old leads the Eredivisie with seven goals in his club's first six league matches. The team has posted a 2-2-2 record in those half-dozen games.
The Alkmaar club now turns its attention back to league play, where it will face RKC Waalwijk at home on Sunday.
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