Another summer recruit, Christian Eriksen, provided Sigurdsson with his double against Norwich City earlier this month, and Freund believes that the 24-year-old is thriving in Tottenham's new-look attack.
"Gylfi is on fire this season, scoring goals and his movement is fantastic from the left coming inside," Freund told the club's official website.
"Again, it was a great lay off from Roberto Soldado and that link with Christian Eriksen is growing. It's looking good."
Sigurdsson has already equalled his three-goal Premier League haul of last season, during which he made 21 of his 33 top-flight appearances off the bench.