Ben Mason of England and Richard Sterne of South Africa top the midway on 10-under-par 136.
Mason, who teed off very early and missed the rain that interrupted play this morning, added a superb bogey-free 66 to his 70 of yesterday. Sterne, who had to sit around for four hours, replied with a 6-under-par 67 to join Mason for the lead.
Fellow Englishmen Denny Lucas and Simon Wakefield are tied for third at 9-under-par, while Jamie Little and Germany's Kariem Baraka are joint-fifth on 8-under-par with Andre Cruse and Ashley Roestoff.
Mason, who led the first three rounds of the Sameer Kenya Open last week, hopes to do better than his joint third-place finish last week.
'After leading three rounds last week in Kenya, I would really like to win this week,' said the 25-year-old from Leeds. Mason collected three birdies on the front and four on the back.
'I am happy with my game. Obviously the ultimate goal is to finish top 15 at the end of the season and a victory this week would help a lot to reach that goal.
'The difference today was my shortgame. I managed to keep it tight on the par-3s and 4s, and went for birdies on the par-5s. And I managed to hole the short putts'.
Sterne started today on the back nine with a birdie run from the 10th to the 14th. He missed 'a silly little three footer' for birdie at the 15th and collected his fifth at the par-4 18th.
He added a sole birdie at the par-5 second and parred his way in for a 67.
'I missed several make-able putts on the front for par,' said Sterne, who was very disappointed to miss the cut last week.
'At the moment I have to apply for invitations to European Tour and Challenge Tour events. A victory this week would guarantee my exemption onto the Challenge Tour, and I will have every chance to try and make the top 15 on the final Order of Merit.
'I just hope to keep my game at this level and get a little luckier with the putter.'
Heavy rain in Lusaka brought an abrupt end to play in the morning. A two-and-1/2 hour suspension followed and play was resumed at 1:30, with only 85 players able to complete their rounds.
Among the 65 players who will return to Lusaka Golf Club at 7:00am tomorrow are first round leader, Mark Murless (65) and Rudi Whitfield (66), who was tied for second after round one.
The second round will resume tomorrow and the third round tee times will be pushed back about three hours. Saturday's forecast called for partly cloudy skies with a 10 percent chance of rain.