In a strongly fought contest, RJC started on the front foot, with a high-pressing game, which meant Lions were just clearing their lines due to not having no time on the ball.
The visitors opened the scoring against the run of play, when a mistake by RJC left-back was punished , and Lions forward was played in and tucked away his opportunity impeccably.
RJC got back into the game, with dominating the ball, but then lacking the final killer ball in the final third.
The Lions doubled their lead after a counter-attack. The initial shot was saved by the RJC B keeper, but the Lions attacker was first to react and tap in.
RJC came fighting out in the second half, and got back into the game instantly , when a corner was delivered by Brad Gayer and was headed in by Ben Chernoff to half the deficit.
The rest of the second half was played In the Lions half, and RJC just couldn't get the equaliser as the Lions defence was standing very strong.
Then in final minute, Lions killed the game off with another counter-attack - as the Lions striker twist and turned the RJC B centre back, and went pass the onrushing keeper and finished the game.
A Lions spokesman commented: "All in all, it was a very positive display with some new faces in the side. If the boys can stick together for the remainder of the season and continue to perform with this much commitment week in week out there might be some rewards with all still to play for."
RJC boss Sam Rank told JC Sport: "Lions A had known they had been in game today, and we wish them good luck in the future rounds. All the RJC B boys can be proud of their performance today, and will be raring to get back to league action next week in a big game against Scrabble."
LIONS: Ryan Springer, Max Hassell, Ben Goldberg, Alex Taylor, Will Beresford, Jamie Jackson, Alex Rose, Ben Lampert, Sam Arghebant, Adam Arnold, Ollie Craig. Subs: Aviel Schwarz, Richard Gold, Louis Torque
SCORERS: Craig (2), Arnold
MAN-OF-THE-MATCH: Ben Lampert