Englishman Paisley and French counterpart Saddier share the lead on 13 under par after returning respective scores of 65 and 63.
The American, targeting a maiden European Tour success, is joined by Jacques Blaauw and Adrien Saddier on the same mark after rounds of six under and one-over par respectively.
Paisley defies odds to beat local boy Grace and win SA Open
"The finish was awesome after making three birdies in a row on 15, 16 and 17", said Saddier. "I have never been in this position before so I am just going to go and do my best".
Retief Goosen, a two-time US Open victor, faltered at the last on Friday with a double-bogey six and lost further ground on the field with a one-over 73 to finish at seven under heading into the final round, while Ernie Els carded a two-under 70 to sit 10 shots off the lead at five under.More news: Arda Turan joins Istanbul Basaksehir from Barcelona on loan deal
"At the moment it is weird - I feel like I did not play fantastic golf".
Chris Paisley and Adrian Saddier moved into unchartered waters while Chase Koepka failed to get into gear in the second round of the BMW SA Open at Glendower Golf Club in the City of Ekurhuleni in Gauteng, South Africa.More news: Espanyol boss Quique Sanchez Flores turns down move to Stoke City
Nearest challenger Kruyswijk, 25, another young golfer eyeing a first European Tour triumph, carded a 67 following a mixed round. If he has a voodoo at that hole he has the exact opposite at 14: he made his third birdie of the week there prior to his 54th hole joy.
South African Retief Goosen, one of the former Major winners, was seven under for the day as he teed off on 18, only to suffer a double-bogey six that left him five strokes off the pace.More news: Trump Gives World Four Months to Change Iran Nuclear Deal
Defending champion Graeme Storm paid for a poor opening round by missing the cut despite a two-under 70 in his second outing, but host Ernie Els will feature at the weekend.