Berger headed into the third and final event in Norway, the 12.5km mass start, having been so dominant on the way to wins in the 7.5km sprint and 10km pursuit.
And it appeared as if Berger, who medalled in every event she entered at the World Championships, winning four golds, would be cruising to a third straight victory in Oslo.
She took the lead for the first time after shooting clear in her first trip to the range and, despite briefly falling behind Darya Domracheva, she had a 20-second lead at the fourth and final shoot.
Berger had gone clear up until that point however she missed two targets to surrender the lead to Anastasiya Kuzmina and face a battle on her hands to win again in Oslo.
However Kuzmina couldn't keep Berger at bay as she recovered from her poor shoot to beat the Slovakian by 5.4 seconds with her final winning time 36:58.8minutes.
Domracheva completed the top three 23.3seconds behind the Norwegian in total and 4.1 ahead of France's Anais Bescond, who shot completely clear, in fourth.
And, with just five races left this season, Berger now cannot be caught at the top of the overall World Cup standings with her lead over Domracheva 321 points.