AUDIO: Lions' losing streak is a 'quick fix'
The Lions, who have lost three of their last four matches, host a Stormers team that has lost four of their seven matches this season.
The Ellis Park showdown is a crucial encounter in the South African conference race – where the Lions top the standings with 20 points after seven matches and the Stormers are joint second (third on points differential) seven points behind.
Victory on Saturday will put the Lions in a commanding position in the conference, but they need a dramatic improvement in form.
Jantjies denied that the last few weeks was a "tough time" for the Lions.
Instead, he described it as a "period of learning".
"It is something that is quick to fix and no major concern," Jantjies said.
"We just need to keep on working hard and the results will come."
Asked what was going wrong, Jantjies replied: "I don't think there is anything wrong.
"we just need to keep on working hard."
The flyhalf, who played for the Stormers in 2013 when the Lions were controversially kicked out of Super Rugby to accommodate the Southern Kings, said he enjoys coming up against his former Stormers teammates.
He particularly enjoyed playing against fellow Bok Siyamthanda Kolisi, whom he described as one of his best friends.
"However, as I said, rugby is rugby.
"It is rivalry and two teams against each other.
"There will be emotion, intensity, there will be a huge effort."