Southern was off form in the second half last week against Dunedin, ending up losing 47-14 after the match was tied 14-all at the break.
Southern coach Luke Herden said the side lost its inside backs in the first half which cost it greatly the longer the game went on.
It was battling injuries as it had all year and had lost winger Josh Gordon (broken jaw) and utility back Bryce Hosie (hamstring) for the rest of the season.
"In the club the two big games of the season are the Cavanagh Memorial and the Ron Reggett. We couldn't win the Ron Reggett last week so this is a big one for us," Herden said.
"We have got a good forward pack in this week and the backline will keep doing what it can do well."
Halfback Liam Howley is scheduled to front and his ability around the ruck will be critical for the team.
With its loss last week, Southern slipped out of the top four but four teams are within three points of each other. Taieri leads the chasing pack on 48 points. University is well out in front on 61 points.
It may well come down to the final game of the season as Southern is set to take on Alhambra-Union at the North Ground next week.
Herden said the side wanted to get six to seven points over the next two games to be comfortable. But the match between Kaikorai and Harbour at Watson Park next week looms as the critical game next week.
Southern is set to field Highlanders lock Pari Pari Parkinson but will be without first five-eighth Josh Ioane who is tied up with the Highlanders.
This will be the last week when Otago players are scheduled to be involved and Southern will only lose Ioane and Hisa Sasagi from next week.
Herden thought players such as loose forward Kyle Harris were unlucky to miss out on selection for the Otago squad but his non-selection would benefit the side.
Southern beat University in the first round and holds the Cavanagh Memorial from last season but knows University will be out to win the trophy.
Southern won the banner last year but has had it tough this season after losing a big group of players in the off-season.
Herden stepped into the role when Paul Miller withdrew because of personal reasons about a third into the season.
Herden said he had thoroughly enjoyed the role.
"It's been a lot of fun. They're a good bunch of guys who create a good environment and work hard."