we get to see some clips of Andy vs Jimmy here, and one of Jimmy's goons (Sweet Daddy O) comes in to help him stomp away at Andy. the crowd doesn't seem to be on either's side at the moment, which is no surprise. so Andy turns to Jerry for help.
now Andy's face turn happens in two weeks. this seems pretty quick to me, watching it this way, but maybe it seemed more natural to the fans then. Jerry certainly seems wary of Andy, but goes along with him anyway.