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The 33-year-old has been battling back to her best form after spending most of last season recovering from hip and knee injuries.
The Cape Town race, which begins at midnight tomorrow (NZ time), will be only Samuels' third race on her comeback trail and is her second-last chance to book a ticket to Rio.
Her last chance to convince the selectors she is ready for the Games would be in Yokohama next month and Samuels was aware she needed to build on where she was at.
"Travel and jet lag aside, it's good to be here [in Cape Town] because I am in desperate need of some good-quality racing.
"That is easily the over-riding factor for me.
"I have only two races under my belt since August, 2014. Therefore, racing is so important to lift my form back to where it was pre-injury and my year and a-half out of competition.''
Samuels finished 20th in both of the last world series events, on the Gold Coast earlier this month and in Abu Dhabi in early March.
However, she was second out of the water on the Gold Coast and her cycling has been solid enough.
It was her running which needed work and Samuels had made progress in that discipline.
"Last weekend on the Gold Coast, I finally had my first good run session since I have been back training, which just reminds me that each week I am making gains.
"All I want out of this race is a reflection of that progress.''
The selection criteria was not clear-cut for Samuels.
A top-three finish would guarantee her a spot in Rio, while a top-eight finish would mean probable selection.
However, Triathlon New Zealand high-performance director Graeme Maw said selectors could use discretion when naming their squad, and Samuels had previously shown what she was capable of.
She finished third in both the World Triathlon Grand Final in Edmonton in 2014, a race which was within the qualifying window, and the World Triathlon in Stockholm a week earlier before getting injured.
Those back-to-back performances gave an indication of her ability when fully fit, and a decent showing in Cape Town would go a long way towards securing selection, Maw said.