“This year has been a great surprise for me, I never thought it would go so well,” De Groot said on Thursday.
“I initially bought my mountain bike just to keep fit, but then I took up a little bit of racing without a sponsor or a schedule and it has gone well.
“I’m really looking forward to Sunday. Lining up and racing to win is the reason one goes to a race and I hope to do the best that I can on the day.”
Both local and international riders were expected to line-up at the one-day mountain-bike event which also featured 30km and 15km races.
In the women’s event, De Groot, who would be taking part in her first off-road challenge race, came in as firm favourite to grab the title from defending champion Yolandi du Toit.
The former road cyclist said she believed her preparations for the race had gone well, while Du Toit, who was recovering from injury, had not yet confirmed her participation.
“My training has gone well and I have been consistent and feel ready to take on the challenge,” De Groot said.
“I don’t know who I will be up against. I hardly look at the entries, so I expect the worst in terms of the competition that will be out there.
“This will be my last big race for the year and I want to ride as best as I can. Mechanical problems popping up will be a big challenge and so I’ll be hoping for the best in that area.”
De Groot started her unsponsored mountain-bike career earlier this year after she retired from professional road racing in 2012, following a successful six year career.
She immediately made her mark on the mountain-bike scene when she was crowned the national mountain-bike marathon champ in June. She outclassed a strong field in the women’s 73km race, to take the title in three hours 33 minutes and 56 seconds.
Later that month, she went on to win the women’s 75km marathon at the MTN Rooiberg event in Limpopo.