The guttural roar was audible seven levels up at Croke Park. The Bulls forwards went through a final stretching exercise. The intensity and focus were unmistakable. And then it was time for eight-on-eight in a series of scrums. There was no brake foot in the collision, no compromise either. Willing to clatter team-mates it was hardly a surprise that they tried to set about Leinster with a feral edge. The opportunity came on 11 minutes. Bulls scrum put in. The best exponents in the URC. A hush descended on the 39,184 in Croke Park, the majority of whom waited with bated breath.The figures don’t lie. The Bulls had a 96.18 per cent success in the URC, had conceded the fewest penalties and won 45 on their own feed. Jerry Cahir’s sporting fairytale was about to face its sternest examination. Scrum. Re-set. Re-set. Collapse. Referee Andrea Piardi waved play on because the ball was at the feet of Bulls number eight, Cameron Hanekom. Play.The explosion of sound from the stands was as much relief as approbation. One down but how many more to go. The answer to that question was six in the opening 40 minutes. Leinster had no need for the worry beads. The scrum survived. No, it did more than that. It shaded the contest in the first half. The only infringement pinged was against the Bulls for chasing across the gap before the put in. Half a dozen chances for the big bad Bulls to assert their primacy. It takes a pack to raise a scrum, must as the village does the child, and every one of the Leinster eight buckled in and toughed it out. Scrumhalf Jamison Gibson-Park got the ball in and out with the sleight of hand of a pickpocket. The last two minutes of the half. Leinster scrum feed. Solid. Unflinching. Leinster put-in again, in their 22, the Bulls loaded up for a monumental surge. Nothing, nada, zip, not a millimetre of go-forward. Leinster studs gripped the Croke Park turf, unyielding.Referee Andrea Piardi watches a scrum at Croke Park. Photograph: Ben Brady/Inpho Another scrum just after half-time. A still picture. It could have been a photograph. No movement until Gibson-Park fished the ball out and kicked long and elegantly into touch in a different postcode. The Bulls finally summoned the frontrow reinforcements. Wilco. In the phonetic alphabet it means ‘will comply.’ The Bulls’ living and breathing incarnation - Wilco Louw - obliged.He and his mates won a scrum penalty on 54 minutes. The Bulls doubled down. Indicated to Piardi that they wished to scrum again. It was 29-0 to Leinster at the time so describing it as a game-defining moment would be a fallacy but for young Alex Usanov on for Cahir and the rest of the replacement front row this was their litmus test. Second time round, the Bulls couldn’t get a run. Had to shift the ball. The home side stared them down. Max Deegan was causing all sorts of problems for the Bulls lineout. So set piece wise, this was Leinster’s night.