Teenage spinner Jack Mockford kept Hawke Cup holders within touch of Nelson on day one of the three-day fixture at Queens Park in Invercargill on Friday.
Southland won the toss and chose to bat first in what is its second defence since winning the Hawke Cup.
James Ng made the best possible start when he bowled opener David Zohrab with Nelson yet to score.
However Zohrab's twin brother Thomas and long-serving first-class cricketer Greg Hay teamed up to put on 134 for the second wicket.
Nelson was in a commanding position but it was leg-spinner Mockford who changed the game.
He took three wickets as Nelson went from 134 for one to 199 for four when the day's play was cut short after 80 overs on day one because of rain.
Southland coach Steve Jackson was delighted Mockford had been been able to pull Nelson back.
"I thought Jack bowled really well today. He had nice flight, nice loop and was really consistent with the areas he was bowling in.
"He got some good wickets, particularly to pick up someone who has the first-class experience that Hay's had, because he was in, he was set.
"He has been working really hard so it's good to see that pay off for him."
Jackson would have liked a couple of more wickets on day one but said Nelson hadn't got away on them run-scoring wise which meant Southland was in a good position to attack with the new ball early on day two.
"At 80 overs you would expect they would be 240 to 250, maybe even 300. So we are pretty happy run wise where we are at. It would have been nice to take a couple of more wickets.
"It 's a pretty good batting deck out there. We've had a couple of chances, a close stumping and a close run out, a couple of good lbw shouts. But the umpires have obviously set the standard for the game and as long as they keep doing that obviously we are happy with that."
Day two will start at 10.30am on Saturday.
NELSON
First Innings
T Zohrab not out 88
D Zohrab b Ng 0
G Hay c Ng b Mockford 72
W Ludick c & b Mockford 7
P Howes lbw Mockford 16
N Clark not out 3
Extras (b 4, lb 1, wd 4, nb 4) 13
TOTAL (for 4 wickets, 80 overs) 199
Fall: 1-0 (Zohrab, 1.2), 2-134 (Hay, 51.2), 3-152 (Ludick, 63.3), 4-183 (Howes, 74.5)
Bowling: J Osborne 10-4-17-0, J Ng 7-1-18-1, J Domigan 21-7-43-0, R Duffy 8-2-36-0, B Lockrose 19-2-53-0, J Mockford 15-3-27-3.