Mo’unga added his fourth penalty and then Will Jordan scored his fifth try in the last three games to maintain their four-year winning streak at Rugby League Park in Christchurch.
The match had been billed all week as the long-awaited reignition of an intense rivalry that stretches back in provincial rugby for more than a century with both teams unbeaten in the New Zealand-only competition.
The near sell-out crowd were not disappointed with the game played at near test-match intensity with the Blues creating immense early pressure.
The early momentum set up a 10th-minute try by Mark Telea before the Crusaders worked their way into Blues’ territory and forced a string of penalties, which allowed Mo’unga to ensure they were only trailing 7-6 at halftime.
The intensity continued in the second half with Black and Mo’unga trading penalties before Ioane crossed, which only sparked the Crusaders’ furious response.
(Reporting by Greg Stutchbury; Editing by Raju Gopalakrishnan)