The 26-year-old was part of a five-strong leading group that quickly fell to four throughout the fourth stage in Italy and this time was the first to cross the finishing line.
Northug had to settle for third behind Russians Maxim Vylegzhanin and Alexander Legkov in the 15km classic pursuit second stage that ended in a sprint finish in Oberhof.
However Northug, going in search of his first Tour de Ski title, wasn’t to be denied as he powered towards the front in the final metres to post a winning time of 1:16:32.
Legkov, third in the prologue that Northug won and second in the pursuit, was 0.7 seconds behind for second while defending champion Dario Cologna finished third a further 0.2 further adrift.
Vylegzhanin the Tour de Ski leader at the start of the day was the last of the breakaway four to finish, 1.6 behind Northug, while fellow Russian Ilia Chernousov was a minute back in fifth.
Despite the gap separating Vylegzhanin in first and Legkov in fifth at the start of the 35km freestyle pursuit, it didn’t take long for all of them to be bunched together.
Canadian Alex Harvey couldn’t match the pace set by them however and was too drop off and fail to catch up with the leading group’s pace destroying the rest of the field.
And Northug, who has won the most stages in Tour de Ski history, showed greater speed to win the spring finish ahead of the 5km classic on Friday.