Fittingly, it was the England-bound former All Blacks prop who laid the basis for Southland's fifth successive Air NZ Cup victory against stubborn opponents still looking for their first away since readmission to the top flight last season.

When Dermody burrowed over the tryline in the 50th minute after a close range lineout the momentum of the ninth round match swung in the home side's favour.

Dermody's try followed two Blair Stewart penalties nailed within five minutes of the restart and, despite Manawatu sticking to their expansive gameplan, they were ultimately ground down by Southland's dominant pack.

Southland improved to fifth on the standings on 25 points with the remainder of the round's matches to come.

They will be overhauled by the winners of the game between Hawke's Bay and Waikato later today but cannot drop out of the top eight with one round remaining.

Despite wet underfoot conditions at Rugby Park, Southland also sought to play an up-tempo approach until it finally dawned on them to revert to their forward-based power and Stewart's accurate kicking game.

He succeeded in pinning Manawatu in their half for most of the second spell, and that territorial dominance translated to 27 unanswered points.

Manawatu also contributed to an enterprising contest, and rode their luck to forge a deserved 11-3 lead at halftime.

Southland opened strongly with Manawatu wing Andre Taylor quickly called on to execute two trysaving tackles.

His second, as blindside flanker Dion Bates dived over in the corner, still resulted in a penalty but shortly after the restart halfback Aaron Good streaked over after smart leadup work from Tomasi Cama and Hayden Triggs.

Taylor was cast as the saviour a third time in the 13th minute when a timely intercept sabotaged a break by fullback James Wilson and, again showing their ability to profit form a letoff, on Manawatu's next sweep downfield Matty James potted a dropped goal.

Wilson came up short with a 53m penalty attempt on the hooter but Stewart was potent from closer range to narrow the gap before Dermody put Southland in front.

Any thoughts of a Manawatu comeback were thwarted by unstoppable Fijian loose forward Noa Soqeta in the 65th minute while centre Jason Kawau wrong footed Francisco Bosch inside the last 60 seconds to ensure Dermody's farewell party started on a high note.

He also gave the crowd something to smile about post-match, indicating he could return to the province to add to his 89 games after a two-season stint with London Irish.

Result of an Air NZ Cup rugby match in Invercargill today:-

Southland 30 (Clarke Dermody, Noa Soqeta, Jason Kawau tries; Blair Stewart 3 pen, 3 con) Manawatu 11 (Aaron Good try; Matty James pen, dropped goal). Halftime: 3-11.