Starting the match-day two points clear of second placed Brackley Town, three points would keep Gateshead top of the league with two games to play.
The Heed got off to the start of their dreams, finding themselves 2-0 up after 12 minutes through Dan Ward and Cedwyn Scott.
Jordan Archer would pull one back for Southport in the first half, but Owen Bailey secured a key win in the title race.
Macauley Langstaff’s early cross was pulled back across the box by Taylor Charters, Ward was there to slam it home and give Gateshead the lead.
Seven minutes later, Scott grabbed his 24th league goal and the Tynesiders’ second of the game as he beat Cameron Mason at his near post.
Gateshead continued their pressure throughout the first half, with Langstaff, Scott and Ward all coming close to making it three before the half an hour mark.
Their best chance of the first half would fall to Carl Magnay, with his point-blank header from an Greg Olley corner being pushed away by Mason.
The visitors showed they were down but not out, as Archer converted Michael Carberry’s cross to see The Port make it 2-1.
Archer made it level for his side before the referee blew his half-time whistle, but the linesman flagged for offside.
Chances were few and far between in the second 45, but Gateshead would craft the clearest chances on goal.
Adam Campbell had a couple of hearted chances prove no real test for Mason, while Langstaff also tested the goalkeeper.
Bailey grabbed his third of the season as he slotted Olley’s lay off past the grip of Mason to send Gateshead five points clear of Brackley Town.