Victory in Saturday’s 10km Gundersen saw Riiber bag his 10th World Cup win from 12 outings this season, also giving him two wins from two in his bid for Triple honours.
A time of 23:28.8 was enough for the Norwegian to take top spot, completing the 10km cross country section more than a minute quicker than Jorgen Graabak, who sits second in the standings.
Sunday will see the Triple completed with the first 15km race of the season.
"I am so satisfied to have managed an even bigger gap to the rest of the competitors today and it is important to have a lot of seconds on Jørgen," Riiber said.
"Hopefully I can be fast on the skis tomorrow and I am crossing my fingers."
Riiber has held the leader’s yellow jersey since the very first race of the season and now has a lead in the overall World Cup standings of nearly 400 points.
He has also become the first man to pass the 1000 points barrier, with the records set to keep on tumbling as the season heads towards its closing stages.