There are three events remaining but such has Frenzel's dominance been this year, the German could afford to slip down to bronze after placing second in the ski jumping.
He has totted up eight gold individual World Cup medals this season but it was compatriot Johannes Rydzek who clinched victory in Lahti.
The 22-year-old, who helped Germany to a team silver medal at Sochi, secured his second World Cup success on the course.
Though down in fourth after 123.7 points in the ski jumping, Rydzek held off Akito Watabe by eight seconds and Frenzel by 21 over cross-country.
Meanwhile, Austria's Wilhelm Denifl, who topped the leaderboard after the jumps, finished down in 13th.
� Sportsbeat 2014
- Sports & Recreation
- Johannes Rydzek
- ski jumping