Wrexham ended Southport's four-match winning run to go level on points with Blue Square Bet Premier leaders Luton.
Home keeper Tony McMillan tipped Wrexham striker Jake Speight's header onto the crossbar in the first half.
Southport's Alan Moogan was sent off just before Lee Fowler had a penalty claims rejected as the Wrexham man felt his shot hit Earl Davis' arm.
A Jay Harris shot and Nathaniel Knight-Percival's header hit the bar for Wrexham, who had Curtis Obeng sent off.
The Dragons, who had lost their previous two games, had another penalty appeal turned down when Obi Anoruo was seemingly pulled back in the area but referee Jeremy Simpson waved away the protests.
VIEW FROM THE DRESSING ROOM
Southport manager Liam Watson told BBC Radio Merseyside:
"You talk about Wrexham being one of the better teams in the league and, if I'm honest, apart the one attempt that Tony McMillian had to slide out, he hasn't had a shot to save.
"For our lads it was like a victory and when we go down to 10 men everybody thinks we're going to cave in.
"A lot of our fans probably thought we would cave in but we dug deep and the pleasing thing is I can't recall Wrexham having a shot."
Wrexham manager Dean Saunders said:
"This was exactly what we needed as we conceded three goals in the last game and three goals the week before that.
"They [Southport] have done well, won four games on trot, have a bit of spirit about them and battled and battled and we did everything but scored.
"We have 20 points from 10 games, which if you took that right throughout the season we would be on 90-odd points.
"I have got to be pleased and for us to bounce back from last week, I think the players have done well."