Southern Districts kept their slim finals hopes alive with an impressive 34-19 win over Randwick last weekend but must beat Manly at home on Saturday to stay in the race for the playoffs.  “Last week was a huge step forward by our guys, particularly playing Randwick at Coogee. We showed composure last week that we haven’t really shown all year,” Rebels coach Don Mackinnon said.  “We’ll need to be patient again this week against Manly, they’re a very good team and will punish you if give them opportunities.” Jed Holloway hasn’t been named to play the Marlins, while gun flyhalf Bayley Kuenzle will also miss the class after getting concussed last week.  Mackinnon has called upon the club’s next generation to fill the void.  “Nathan Lawson and Daniel Bell are both local juniors. Daniel is in his first year of grade and Nathan is still a colt.  “Cooper Chambers at scrum half is still eligible for colts next year and has come through our junior ac