They lay and drove together during Sunday's chase start over 10 km classic and then lost uphill but caught up downhill on the willing Karlsson and Udnes Weng was able to win his first victory in the Tour de Ski and the World Cup.
By the start of the hunt tomorrow, Frida Karlsson hopes that the lead of 20 seconds will be extended even more to what she refers to as "hungry wolves".
The Norwegians have another hope.
- Frida got us a small slot so we get to hunt her tomorrow.
It will be a tough fight and there are many of us girls who are there fighting for the podium places, so it's fun, says Kalvå to Finnish Yle.
It will be below zero in Oberstdorf
Today's rain should stop and there should also be some occasional minus degrees during the early morning in Oberstdorf, which will give firm and hard tracks at the start at 2.30 pm.
Yesterday it was summer heat with 18 degrees.
The men will first drive the same course at 11.15.
- It is difficult to predict because it is a tough course and a long race tomorrow, says Kalvå if she believes that the competition lives until Sunday with the tough finish up Alpe Cermis.
Jessie Diggins, who won the entire Tour de Ski two years ago, is out of podium discussions after another lackluster race.
She is only 36th over four minutes behind Karlsson.
Norwegian experts think she should break the tour and try to find her form for the WC at the end of February.
- I had pretty good energy, but I made a mistake and didn't ask for enough grip, and for me it's very difficult to ride then, says Diggins to SVT Sport.
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Ebba Andersson believes that her friend Frida Karlsson has a great chance of winning the Tour de Ski Photo: Bildbyrån/TT