Playing in the morning groups on Friday, Dobbelaar backed up a round of five-under 67 on day one with a score of six-under 66 to move to 11 under and the outright lead.
Yeo, who went within a whisker of Ryan Fox's course record on Thursday, added two early birdies to his overnight score of nine-under 63 to join Dobbelaar in the lead.
After starting on the back nine, Yeo improved his score by three strokes from the day before at the par-5 17th to move one clear at 12 under only to come home with two birdies and three bogeys to sit level with Dobbelaar at the halfway mark.
They have a three-shot advantage over Australian trio Gavin Fairfax (68), Matias Sanchez (70) and Jarryd Felton (71) and Japan's Ren Yonezawa (69) with Matthew Griffin (66), Justin Warren (67), Will Florimo (70) and Jordan Loof (71) in a share of seventh at seven under.
Having never made a cut in nine previous starts on the PGA Tour of Australasia, it is uncharted waters for Yeo as Dobbelaar seeks to feel the competitive heat of professional golf once again.
"When you're in a bit of a situation, you have more reason to focus," Dobbelaar said of his lofty position on the leaderboard.
"That definitely engages me a bit more but I've been trying to be like that from the start of events lately and been playing a bit more solid."
