Van den Berg and Swede Mattias Nilsson are only one shot clear of a bunched leaderboard. South Africa's Graeme van der Nest and the Zimbabwean trio of Nasho Kamungeremu, Sean Farrell and Mike Lamb opened with rounds of 68.
Defending champion James Loughnane is five shots off the pace after opening with a modest 1-under par 72. Zimbabwe's Marc Cayeux, another former champion of this event, also carded a 72 on the first day, while Ashley Roestoff, winner of last week's Kenya Open, returned a level-par 73.
The par-73 Lusaka Golf Course was playing incredibly long on the first day following some heavy rain in the area. But a relaxed Van den Berg played patient golf that yielded six birdies and no bogeys.
'The course is still quite wet and the greens are bumpy, so you have to be patient,' he said. After the stress of the recent summer section of the tour, Van den Berg decided not to play in last week's Kenya Open and instead took a week off.
'I really needed a break and never touched a club the whole week. The summer tour was very stressful for me because I didn't play as well as I wanted to. I had a few good finishes, but it felt like I was continually fighting against the odds. I felt like my game was there, but it just wasn't clicking.'
Van den Berg is hunting his second victory on the Sunshine Tour after he broke through with a win in last year's Riviera Classic. The young Johannesburg professional was also fortunate enough to see his playing partner Andre Cruse score a hole-in-one at the par-3 11th that wins Cruse a Nissan Terrano 4x4 worth over R200,000.
'He literally jumped into my arms when the ball dropped in,' said Van den Berg.
Kamungeremu was one of the round's early leaders. The burly Zimbabwean managed to climb to 8-under par after 11 holes following a run of six birdies and an eagle. But he ran into trouble midway through his second nine, succumbing to four bogeys in six holes that offset a solitary birdie on that nine.
Kamungeremu's last victory on the tour was in the 1997 Botswana Open, and he has since struggled to recreate that form. 'I've been grinding year in and year out, and it's just a matter of putting four good rounds together which is something I've had a problem with,' he said.
'I seemed to do everything right for those first 11 holes. But that first bogey affected my concentration and I wasn't playing with the same confidence after that,' said Kamungeremu, who finished top of last year's Order of Merit on the Zimbabwean Tour.