Horouta have had two wins against OBR but they came unstuck against HSOB last Saturday, bowled out for 66.
OBR have had their own troubles with the bat but look a strong unit in the field.
Horouta captain David Situ said he would demand a total effort from his side.
“In a knockout game, there’s more to play for,” he said.
“We had a disappointing game last week and definitely want to come back strong against OBR.”
OBR senior bowler Matt Cook said it was a must-win game for the club.
OBR had shown in one of their games against HSOB that they could get it right with the bat, he said.
“The runs will come but we have to be patient and not give our wickets away.
“We need a combined effort.”
Cook said OBR were rebuilding, as they were fielding a younger line-up this season.
If OBR produce the goods tomorrow, their reward will be a final against their “old foes”.
Cook said OBR and HSOB had a long rivalry.
“Everyone steps up for those games.”
But OBR must get past Horouta first.
The game is due to start at 1pm and the MetService forecast is for fine and warm weather, with a high of 28 degrees Celsius.