The hosts made all the play early and second five-eighths Tevita Latu scored a seventh-minute opening try, running a crash ball one out from an attacking scrum.
Hawke’s Bay immediately cranked up their rolling maul, forcing consecutive penalties for collapsing before Tyrone Thompson burrowed over the tryline.
Southland held significant possession and territorial advantages over the first quarter of the game, but struggled to hang with the Magpies whenever the visitors put phases together.
No 8 Marino Mikaele-Tu’u’s 24th minute try gave Hawke’s Bay their first lead.
They threw away possession at times but were able to win the ball back through utterly dominant scrummaging.
Hawke’s Bay blindside Josh Kaifa extended the lead to 12 just before halftime with a try following a scrum five metres out.
Despite the Stags’ dominance of possession and territory, the Magpies gained 297 metres in the first half to just 125 for the hosts.
Brad Weber scored the try of the day in the 49th minute, finishing off a beautiful flowing move that started from a scrum on halfway.
Both teams emptied their benches by the hour mark as Southland replaced Connor McLeod at halfback.
The former St John’s College student, who played 13 games for Hawke’s Bay between 2020 and 2022, is on loan at the Stags with Weber and Folau Fakatava sharing almost all the Magpies’ minutes at No 9 this season.
Southland thought they had their second try in the 60th minute but left winger Gabe Hamer-Webb stepped on the sideline just before dotting the ball down in the corner.
Weber had a strong game but Fakatava showed his X-factor in setting up Hawke’s Bay’s fifth try.
The 23-year-old’s left-foot sidestep shook off a handful of would-be tacklers and he strolled in under the posts before gifting the ball and five more points to Josh Kaifa.
The win put Hawke’s Bay into the top four as of Saturday afternoon and, should they defeat Wellington next week, they could secure a home semifinal, depending on other results.