The four time champion said she was familiar with the venue and hoped to make it five out of five championships.
Since making the switch to mountain biking in 2013, De Groot has won the marathon title every year.
“I’ve raced three events in Pietermaritzburg, so it should hopefully be a great ride,” she said.
De Groot’s season has been filled with a number of near misses so far as she finished third overall at this year’s Cape Epic with Sabine Spitz.
“Form-wise, it was a good Epic, and I’m happy with how we did, but it was very challenging as we faced many hiccups along the way.
“But that’s all part of mountain biking, isn’t it,” she said.
The sani2c title also evaded De Groot as she partnered with Mariske Strauss for the three-day event.
Despite their best efforts, the pair finished third after the second stage was declared neutral due to poor weather conditions.
The women’s marathon will cover 60km while the men’s event has been shortened to 80km.